TH 7222 
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Book._^il4iL_ 



CojpgMN?. 



COFVRICHT DEPOSIK 



VENTILATION 



FOR 



DWELLINGS, RURAL SCHOOLS 
AND STABLES 



BY 



F. H. KING 



Formerly Professor of Agricultural Physics in the University of Wis- 
consin. Author of ' ' The Soil; ' ' ' 'Irrigation and Drainage; ' ' 
' 'Physics of Agriculture. ' ' 



* • • 




MADISON. 


WIS. 


Published by th( 


g Author 


1908 





LIBRARY cf CONGRESS 
Two Copies Received 

DEC 18 1908 

Copyriifot tntr 

euss flu xXt^Mo, 
■LZ7.5Z.0 

COPY a. 




"Copyright, 1908 

byf. h. king. 

All rights reserved- 



V>3 



PHYSICS OF AGRICULTURE 

By F. H. KING 

Professor of Agricultural Physics in the University of Wisconsin, 1888-1901 ; 
Chief of the Division of Soil Management, U. S. Department of Agricul- 
ture. 1901-1904. 

Author of "The Soil." 1895 ; "Irrigation and Drainage," 1899 : "Tillage, Its 
Philosophy and Practice," "The Necessity and Practice of Drainage," in 
Cyclopedia of American Agriculture, 1907 ; "Drainage" and "Irrigation," 
in The Standard Cyclopedia of Modem Agriculture, (British), 1908. 

Fourth Edition, 604 pages, 7%x5% inches, 176 illustratio'ns. 

Published by the author, Madison, Wis. Price $1.75 



CONTENTS 

Ihtroduction 6- 48 

SOIL PHYSICS 

Nature, Origin and Waste of Soils 49- 68 

Chemical and Mineral Nature of Soils . 69- 91 

Soluble Salts in Field Soils 92-107 

Physical Nature of Soils 108-128 

Soil Moisture 129-141 

Physics of Plant Breathing and Root Action 142-157 

Movements of Soil Moisture 158-203 

Relation of Air to Soil 204-211 

Soil Temperature 212-222 

Objects, Methods and Implements of Tillage 223-254 

GROUND WATER, WELLS AND FARM DRAINAGE 

Movements of Ground Water 255-274 

Farm Wells 275-285 

Principles of Farm Drainage 286-310 

Practice of Underdrainage 311-328 

PRINCIPLES OF RURAL ARCHITECTURE 

Strength of Materials 329-342 

Warmth, Light and Ventilation 34.3-365 

Principles of Construction 366-393 

Construction of Silos 394-427 

FARM MECHANICS 

Principles of Draft 428-443 

Construction and Maintenance of Country Roads 444-485 

Farm Motors 486-537 

Farm Machinery 538-553 

PRINCIPLES OF WEATHER FORECASTING 

The Atmosphere 554-560 

Movements of the Atmosphere 561-577 

Weather Changes 578-592 

"All in all, this is the greatest and best collection of modem agricultural 
scientific facts, practically applied, that we have seen. Anyone, whether he be 
a farmer 6v not or whether he be a student in a college or an old man in the 
field, can learn a great deal here. It is a mine of correct information. We 

shall value it highly as a work of reference." — Ohio Farmer, March 27, 1902. 



CONTENTS 



INTRODUCTION (pages 1-44) 

PAGES 

Nature's Provision for VsNTiiiATioN of Body Tissues 3- 8 

Amount of Air Required for a Daily Ration 8- U 

Air Once Breathed has Lost Much of its Sustaining Power 11-17 

A Continuous Flow of Air is Necessary 17- 19 

Fresh Air Supply certain to be Inadequate at Times if Definite 

Provision for it is not Made 19- 24 

Serious Effects Follow Insufficient Ventilation 24-31 

Volume of Air Which Should Move Continuously through 

DWELINGS AND StABLBS 31- 45 



PRINCIPLES OF VENTILATION (pages 45-75) 

Power Used in Ventilation 46- 64 

Maintenance of Temperature with Ample Ventilation 64-75 

PRACTICE OF VENTILATION (pagres 76-126) 

Best Room and Stable Temperature 76- 78 

Light for Dwellings and Stables 78- 88 

Ventilation of Dwellings 88-102 

Ventilation of Houses Already Built 90- 94 

Warming- and Ventilation of New and Remodeled Houses 94-102 

Heating and Ventilation of Rural School-houses and Churohes102-106 

Stable Ventilation 107-126 

Ventilation of Dairy Stables 109-120 

Ventilation for Swine and Sheep 120-123 

Ventilation of Poultry Houses 123-126 



PREFACE 



In the preparation of this brief treatise the aim has been 
to reach parents, teachers and school officers of rural and 
other elementary schools, and the owners and caretakers of 
all classes of live stock, and lay before them the' founda- 
tion facts and principles underlying the growing and im- 
perative demand for a more nearly adequate supply of 
pure air than is being continuously maintained in the vast 
majority of home's, offices and stables today. 

In presenting the subject the effort has been to make 
the treatment suggestive to teachers, introducing lines of 
simple experimentation and arithmetical calculations, so 
that they may more surely enlist the attention and coop- 
eration of their community in the immediately practical 
aspects of the subject. It is hoped, too, that all owners 
and caretake'rs of live stock will find the treatment of 
stable ventilation sufficiently explicit and illustrative to 
enable them to readily and effectively solve their own prob- 
lems. 

In applying the principles used in stable ventilation to 
dwellings, office's and school-houses, where mechanical ap- 
pliances or hot air furnaces are not used, we are convinced 
that there are no practical difficulties in the way and that 
when such a system of ventilation is combined with the 
warming as suggested it will be found thoroughly efficient. 
In the effort to be brief, and yet have the presentation 
sufficiently fundamental and explicit so as not to mislead, 
it has been necessary, in the treatment of dwellings and 
schools, to omit details, yet it is hoped enough has been 
given so that with the aid of builders and local architects 
installations may be readily made. 

F. H. King. 

Madison, Wisconsin. 

Nov. 23, 1908. 




"And did it occur to you that here, too, was another bellows feeding 
air into another forge, keeping the fire of life aglow and timing its 
Intensity to the work to be done?" — Page 1. 



INTEODUCTION 



Have you stood in a smithy's door and watched the cold 
bar of iron mount by quick steps to a white heat as the 
strong arm on the bellows compelled fresh air through the 
bed of coals on the forge ? Did you reflect that that inter- 
mittent air current contributed more pounds avoirdupois to 
the. generation of the heat than did the coal, in the ratio of 
about 8 to 3 ? Did you note the capacity of the huge bel- 
lows, the powerful lever with which it was worked, the 
length of the strokes and the weight which the smith threw 
onto the bellows to feed sufficient air to his forge ? Did you 
note the rythmical rise and fall of the smith's deep chest 
as he moved about his work? How the heaving quickened 
and deepened as the blows from the hammer fell more 
swiftly and with greater force upon the shaping piece? 
And did it occur to you that here, too, was another bellows, 
feeding air into another forge, keeping the fire of life aglow 
and timing its intensity to the work to be done ? 

Did you observe how thoroughly the smith kept drawing 
up over his fire a blanket of cinders and coal, that the heat 
should be retained where the work was being done and that 
as little as possible should be wasted ? And did you realize 
how much more this greater economy made the action of the 
bellows necessary to carry sufficient air to the exact place 
where it must be used ? And do you realize with what con- 
sumate economy all the forges of life, whether of man, 
beast, bird or bee, have been housed in from the cold and 
are continuously fanned, whether waking or asleep, by au- 
tomatic bellows, thus generating the maximum of energy 
with the minimum of fuel and of labor ? 



2 Ventilation. 

Now when the best results from the forge demand a con- 
tinuous action of the bellows, feeding in more than 11 
pounds of pure air through the fire for each pound of coal 
burned, and when the health and best action of the smith 
demand more than 20 cubic feet of pure air per hour, what 
would you think of setting up and operating, in an 8 by 8 
room without chimney and with doors and windows closed, 
such a combination of forge and man during ten consecu- 
tive hours, depending for the renewal of air upon such 
leakage as may take place through walls and ceiling? And 
yet are not conditions more deplorable than these found in 
many a sleeping chamber, stable, bee-hive, factory and 
church? Do we not realize and generally practice in ac- 
cordance with the fact that closing the drafts in a stove 
checks the intensity of the fire or extinguishes it altogether ? 
Do we not understand perfectly that the proper action of a 
stove or of a furnace can only be secured through the ef- 
fective action of a good chimney? Do we not know most 
thoroughly that we may go for days without food, and even 
without water, but that to be deprived of air for only a few 
minutes results in the greatest distress and may even prove 
fatal? Have we not felt the oppression which follows the 
closing of ventilators and windows of a crowded coach for 
only a minute or two to shut out the smoke while the train 
passes through a tunnel, and do we not recall how everyone 
is looking anxiously for the windows and ventilators to be 
opened the moment the train emerges ? 

How can it be, then, that today, even in cities where 
homes are planned by trained architects, little or no thought 
is given to making special provision for ventilation in the 
majority of dwellings. First of all, must not the house be 
cheap, then if it can be warm, light, convenient, commod- 
ious and attractive are not these clear gains? If we can 
cook, wash and iron with gasolene, a blue-flame oil stove, 
gas or electricity, then may not the expense of one chim- 
ney be saved? And if we will heat the house with hot 
water or with steam may not every room then be as nearly 
an air tight box as the materials and the mode of construe- 



Ventilation of Body Tissues. 3 

tion makes possible ? And with such arrangements may not 
the work and the warming of the house be done with the 
least possible expense for fuel? Most certainly, but how 
about the health and comfort of the family for whom the 
home was built? Which is better, a close house with but 
little air, to be breathed and burned over and over again, 
with langour and irritableness, and perhaps less of service 
through sickness and a large doctor's bill, or an airy home, 
full of buoyancy, cheer and health but perhaps a trifle 
larger bill for coal? 

Is it urged that the wind will force air enough through 
the house and stable even with the closest possible construc- 
tion ? But how about the days and the nights when there is 
little or no wind ? Then the windows may be opened ? But 
who thinks to do this at the right time? Perhaps the one 
in the family who suffers most from insufficient change of 
air is too unselfish or too sensitive lest some one else would 
be disturbed by opening the windows, or perhaps the herds- 
man has too little thought for the animals in the stable to 
take the necessary trouble at the proper time. Clearly, if 
an abundant change of air is needful, a flow should be con- 
tinuous and sufficient at all times, whether we are awake 
or asleep, and whether attention is given to it or not. That 
an abundant change of air in the house or in the stable is 
needful there can be no doubt, and that this cannot take 
place unless proper arrangements are provided for it is 
likewise evident. 



NATIJRE S PROVISION FOR VENTILATION OF BODY-TISSUES. 

So great, so imperative and so constant is the need of 
fresh air in the maintenance of vigorous bodily functions 
that the delicate lining membrane of the lungs of an ordi- 
nary man, in contact with which air is brought and through 
which all the blood of the body circulates, were it spread 
out in a continuous sheet, would measure no less than 236 
square feet, enough to cover the sides, floor and ceiling of 



4 Ventilation. 

a room more than 6 by 6 by 6 feet, and that of a 1000-pound 
cow would similarly cover a room 11 by 11 by 11 feet. 




Plg^. 3.— The area of this room, walls, floor and ceiling, 6 by 6 by 6 feet, 
represents the amount of surface in the lungs of an ordinary man 
through which all the blood of the body passes about twice every 
minute, to be brought close to the air which is changed by the act of 
breathing 15 to 20 times per minute. 



Such enormous surfaces as 236 square feet of delicate 
lining membrane, in the lungs of man, and of 1,500 square 
feet in those of the cow, may seem impossible. That this is 
not so may be understood when it is said that a box one foot 
on each side has an inside surface of six square feet. Pass 
a partition through the center of this box each of the three 
ways. The eight chambers so formed have double the ag- 
gregate inside surface of the original box, or twelve square 
feet per cubic foot of space. By passing ten planes through 
the box in each of the three ways we would increase the in- 
side surface ten-fold, giving it 60 square feet, and so 40 
such partitions passing in each of the three directions would 
increase the inside area 40-fold, giving just about the lung 
surface for man, and yet each of the 64,000 small chambers 
so formed, three-tenths of an inch on a side, would be very 
much larger than the actual air-cells in the lungs. In the 



Extent of Lung Surface. 5 

box represented in Fig. 3, subdivided by 40 planes passing^ 
each way, the small divisions are each one-twelfth of an 
inch in diameter, easily visible, and the total wall surface 
formed by them measures no less than 18.5 square feet and 
about one-twelfth the lung surface of man, thus making it 
clear how a very large surface may be developed in a smaD 
space. 



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Fig. 3.— A box the size of this drawing, subdivided by as many parti- 
tions as are represented by the lines, would form 64,000 chamber* 
having a total wall surface of 18.5 square feet, one-twelfth that in the 
lungs of an ordinary man. 

Now imagine blood flowing steadily through a close net- 
work of capillaries within all the partitions in this box, 
and at the same time, by a bellows-like action, that the air 
is drawn into and forced out of it 15 to 20 times every 



6 Ventilation. 

minute, and you have, then, a fairly truthful illustration of 
the principle underlying the mechanism by which the blood 
of the body is brought continuously into close touch with a 
fresh supply of air. The blood vessels, bringing all of the 
blood of the body to the lungs, subdivide and spread out 
until they expose to the air in the air-cells some 236 square 
feet of blood surface, flowing in the thinnest possible 
streams almost in touch with air on two sides, which is 
being renovated by 15 to 20 respirations every minute, 
while the powerful action of the heart drives the whole 
blood of the body over this large surface once every 20 to 
40 seconds. 

There is another remarkable feature in the wonderful 
mechanism which nature has found necessary to make sure 
that oxygen shall be brought to and carbon dioxide re- 
moved from the body tissues as rapidly as is needful. The 
water of the blood, although comprising 80 per cent of its 
weight, does not have a sufficiently strong absorbing power 
to permit it to take up oxygen in the lungs, exchanging it 
for carbon dioxide in the tissues, as rapidly as is needful 
and hence more than half the volume of the blood is put 
into the form of circular, cracker-shaped disks called the 
red corpuscles, giving its characteristic color. These cor- 
puscles strongly absorb oxygen when in the lungs and ex- 
change it for carbon dioxide when in the tissues, thus act- 
ing like so many conveying buckets which are continuously 
loading and unloading with each round trip and yet with- 
out stopping. Moreover, to make sure that each one of these 
carriers shall be brought in touch with air before it can re- 
turn to the body, the diameters of the capillaries are made 
so small that these absorbing disks are compelled to pass 
through them almost in single file with both faces almost 
continuously in touch with the lining membrane of adjacent 
air cells, thus insuring ample opportunity for the unloading 
of the carbon dioxide brought from the tissues, and for the 
reloading with oxygen to be carried back. 

There is represented on the right in Fig. 4 a face view 
-with a cross-section of one of these oxygen and carbon diox- 



Carriers of Oxygen-food. 7 

ide carriers magnified some 2,650 diameters, and on the left 
a single capillary with the corpuscles passing through it in 
single file. 



Pig. 4; — Here is seen, on the right, the shape of the oxygen and carbon- 
dioxide carriers in the blood of man, magnified 3,650 diameters and, 
on the left, a line of them passing single file through a capillary, 
magnified about 600 diameters. 



These carriers of oxygen-food to the body tissues and of 
carbon-dioxide-waste from them, although so extremely 
minute, are yet so numerous that the total surface of the 
corpuscles in the blood of an ordinary vigorous healthy 
man measures no less than 49,000 square feet, or more than 
a full acre. Think of the heart, with its 70-odd strokes per 
minute, sending more than a full acre of bucket faces 
through the 236 square feet of partition surface in the 
ventilation chamber of the body once every 20 to 40 sec-^ 
ends, and the air of this chamber changed 15 to 20 times 
every minute ! Nor is this the whole story of the structural 
arrangements in the mechanism of breathing by which the 
body tissues shall be fed oxygen and freed from carbon-di- 
oxide-waste, for it is at once clear that the flattened shape 
of the blood disks gives to them not only the largest ab- 
sorbing surface but at the same time it provides the short- 
est possible distance over which these gases must travel to 
enter, and leave the tissues, which must take place by the 
only available but peculiarly slow process of diffusion. 

Everything, therefore, points to the most imperative need 
of a thorough ventilation of the body tissues. But when we- 
are brought to realize how superlatively efileient this mech- 



-8 Ventilation. 

anism for breathing is we can never afford to forget that it 
grew into its marvelous efficiency unhampered by any of 
the restrictions or constrictions imposed by fashion, and 
when all of the breathing was done in the pure free air of 
field and forest. Nature has provided a very large margin 
of safety in this, as in other matters meaning life or death 
to organisms which are the present survivors of uncounted 
generations which have come and gone. For such as are 
content to bestow their affections upon pug dogs while they 
give their lives to the amusement of a brotherhood enter- 
taining if possible less lofty aims in life perhaps the world 
need not be concerned ; but for those who project their lives 
into the future may God and all the forces which conspire 
to better living do everything possible to make deep breath- 
ing easier and more certain and to maintain a standard of 
purity of air in the home and in the stable which ap- 
proaches closely that in the open field. It is along such 
lines of the fullest utilization of our natural resources, even 
more than to the husbanding of them, .that we need to look 
if a race shall be perpetuated capable of highest civilization 
and which will be lead on by higher ideals. How can we 
hope to combat disease, maintain and transmit bodily vigor, 
when the very breath of life is shut out of our bodies by 
thoughtless false standards of dress and from our homes 
and stables by lack of sufficient thought given to proper 
construction ? • 

AMOUNT OP AIR REQUIRED FOR A DAILY RATION. 

The complete consumption of a pound of hay or of grain, 
in the body of an animal, converting it into carbon dioxide 
and water, would require the same amount of oxygen as 
though it were burned in a stove or on the grate of an en- 
gine boiler. Speaking in approximate round numbers the 
burning of a pound of hard coal requires all of the oxygen 
carried in some 11 pounds, or 136 cubic feet, of air and the 
burning of one pound of hay requires all the oxygen in 
.some 5 pounds or 62 cubic feet. But when rapid and com- 



Amount of Air Required Dadly. 



9 



plete combustion takes place not all of the oxygen in the 
air can be consumed and hence much more than 136 cubic 
feet of air per pound of coal, and than 62 cubic feet per 
pound of hay, must pass through the fire box for each 
pound of material consumed. Moreover it is important to 
keep in mind that air is as much a part of the fuel which 
produces the fire as is the coal or the wood, indeed, even 
more so when considered pound for pound. And so is the 
air an animal breathes as much an indispensable part of the 
food it consumes as is the hay or the grain eaten. In the 
furnace neither can burn without the other and so, within 
the animal body, neither assimilation of food nor genera- 
tion of energy can take place without the consumption of a 
proportionate amount of air. When an engine is being 
crowded to its full capacity in the generation of power not 
only must the stoking be more rapid but the drafts also 
must be opened wider that more air may pass through the 
fire ; and so it is with an animal when doing work, no mat- 
ter of what kind, it must breath more deeply or more fre- 
quently. We realize this clearly in our own case and we 
see it in the horse, the ox or the dog, when they are in vio- 
lent exercise. Even in the case of the heavy feeding of 
animals for the production of milk or of flesh proportion- 
ately more air must be breathed, and hence when animals 
are closely housed under these conditions more air should 
pass through the stable each day. 

The amount of pure air which must be breathed by differ- 
ent animals during 24 hours, in order to supply the oxygen 
needed, computed from Colin ^s table, is given below: 



Amount of air 'breathed ly different animals. 


Per hour. 


Per 24 hours. 




cu. ft. 


lbs. 


cu. ft. 


Volume. 


Horse 


141.7 

116.8 

46.0 

30.2 

17.7 
1.2 


272 

224 

89 

58 

34 

2 


3401 

2804 

1103 

726 

425 

29 


15 X 15 X 15 ft. 


Cow 


14 X 14 X 14 ft. 


Pig- 


10 X 10 X 10 ft. 


Sheep 


9x .9x 9 ft. 


Man 


8 X 8 X 8 ft. 


Hen 


3 X 3 X 3 ft. 







10 



Ventilation: 



From this table it appears that a horse must draw into 
and force out of his lungs, on the average, each hour, some 
142 cubic feet of air, the cow 117, the pig 46, the sheep 30 
and the man 18 cubic feet. These volumes are represented 
in Fig. 5. 







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Pig. 5.— Here each small square in tlie illustration represents one foot 
and each pile of cubes the volume of air breathed each hour, which 
should be nearly pure. 



If it were necessary to supply air to our stock as we do 
water the horse would require continuously 7 full pails per 
minute; the cow, 6; the pig, 2.3, and the sheep, 1.5 full 
pails of air, and these are the amounts required when it is 
supplied pure and fresh with each respiration, as would oc- 
cur out of doors where there is a free air movement and 
where the air thrown off from the lungs is at once borne 
away by the winds. Inside a dwelling or stable the condi- 
tions would be very different unless some means were pro- 
vided to maintain a constant change of air at the proper 
rate. 



Air Breathed Loses in Sustaining Power. 



11 



AIR ONCE BREATHED HAS LOST MUCH OF ITS SUSTAINING 

POWER. 

Air once breathed has lost much of its food value or sus- 
taining power and, impossible as it may seem we have 
known horses to suffer from breathing Impoverished ^^^ 
when plowing m the open field. This may occur where 
three horses driven abreast have their heads close aid so 
directed that the middle animal is compelled to draw hk 

hfei; r '""V"^'' '""'^'^ °"t by the other two and 
,the exhaustion or fatigue of the center horse can oftm be 

made noticeably less when a " spreader " or the habit of driv! 
mg requires the outside animals to breathe straight in front 
or a httle outward. Three heavy horses at ha?d laborTn 

mg value to such an extent that when the outer horses are 
permitted to travel a little in advance and at the same time 
mcline their heads in, the center animal is placed at a gre"t 
disadvantage m being compelled to breathe partly 2 
hausted and otherwise viti- 
ated air, for the case is like 
feeding the firebox of one en- 
gine from the smokestacks of 
two others. So, too, when a 
large number of sheep are 
driven long distances in a 
closely huddled flock much 

discomfort results from their 

being compelled to breathe 

exhausted air. 
Everyone has observed that 

of two glowing coals in the 

open air the one which has a 

strong current forced across 

it burns more rapidly and with a more intense glow. Why 

is this? Clearly because one has a more rapid change of 

air, IS better ventilated, even though both may be out of 

doors. Immediately about the burning coal the oxygen of 




Fig. 6.— The air blown across 
one coal increases the glow. 



12 



Ventilation. 



the air is both partly exhausted and diluted, and the cur- 
rent drives the used air away, bringing fresh air instead. 
And so ventilation, even out of doors, may be helpful. The 
lamp without a chimney gives little light and smokes badly 
but the flame surrounded with a chimney, which seemingly 
shuts off the free access of air, burns much better and 
simply because it gets a more rapid change of air. The 
chimney compels a stream to flow rapidly close to the flame 
and thus is swept away the used air while a fresh supply 
takes its place. And so, the lamp, the stove, the engine and 
the forge, whether in an enclosure or out of doors, must 
have a mechanism securing a continuous forced change of 
air; and the respiratory movements of every air-breathing 
animal tell of the same imperative need. And yet, dwell- 
ings and stables are planned, adopting increasingly close 
•construction, allowing ventilation to be brought about inci- 
dentally as it may, without special provision. Only last 
summer in conversation with a New York City architect it 
appeared that he had recently completed a residence in ce- 
ment concrete and was much surprised to find that the fire- 
place would invariably smoke 
unless a door or window of 
the room was open. 

Here is perhaps a more 
striking demonstration of the 
need of ventilation and of the 
fact that air once breathed 
has lost in sustaining poweT. 
In the illustration. Fig. 7, 
from a photograph, a coil of 
magnesium ribbon is shown 
burning in ordinary air sup- 
plied by convection currents 
through the open mouth of a 
two-quart Mason jar. The 
intense light which fills the 
jar and the cloud of white smoke escaping above show 
how strong is the burning; while in Fig. 8 is shown 




Fig. 7. — Magnesium ribbon 
burning in ordinary air. 



Composition of the Atmosphere. 



13 



a similar piece of the same ribbon burning in the same jar, 
but here supplied with air from the lungs, conveyed 
through the rubber tube. Very 
markedly less intense is the 
burning and the light pro- 
duced in this case, and far 
less is the cloud of smoke. 
It is of course the' diminished 
volume per cent of oxygen 
carried by the respired air 
which causes the difference in 
the intensity of burning, for 
the rate of change of air is 
greater in this case. 

The composition of pure 
dry air and of air carrying 
75 per cent of its saturated 
volume of moisture, deduced 
from data of Clarke published 
in 1908 from the most recent 
and authoritative determina- 
tions, are given in the next 
table : 




Pig. 8. — Magnesium ribbon 
burning in respired air. 



Composition of the Atmosphere. 



Dry air: 

Carbon dioxide 

Oxj^g-en 

Nitrog-en and otlier g-ases 

Air. humidity 75 per cent : 

Carbon dioxide 

Oxygen 

Nitrogen and otlier gases 
Moisture 



Volume 
per cent. 



.0292 
20.941 
79.030 

.028 

20.582 

77.677 

1.713 



Cubic inches 
per cubic foot. 



.506 

361.860 

1365.634 

.484 

355.657 

1342.256 

29.603 



14 



Ventilation. 



On the average, in the case of man, it is found that once 
respired air has lost oxygen to the extent of 4.78 volume 
per cent. It has acquired 4.35 volume per cent of carbon 
dioxide and has become saturated with moisture at the tem- 
perature of the respired air, while its volume has been in- 
creased by the expansion due to the rise in temperature. 
Each of these changes reduces the absolute amount of oxy- 
gen which may enter the lungs in a given time when the air 
is respired again, unless the depth or frequency of breath- 
ing is increased. 

The changes in composition which come to once breathed 
air are indicated in the next table, where dry air and that 
75 per cent saturated with moisture before breathing are 
the basis of computation. 

Composition of pure air and of that once breathed. 



Dry air: 

Oxygen 

Carbon dioxide 

Nitrog'en and other gases. 

Moisture 

Air. humidity 75 per cent : 

Oxyg-en 

Carbon dioxide 

Nitrogen and other gases. 

Moisture 



Pure air, 

cubic inches 

per cu. ft. 



361.860 

.506 

1365.634 



355 . 657 

.484 

1342.256 

29.630 



Airbreathed. 

cubic inches 

per cu. ft. 



'265.920 
72.059 

1300.400 
89.638 

264.330 

73.232 

1300.800 

89.638 



Change, 
cubic inches 



—95.94 

+71.553 

—65.234 

+89.638 

—91.327 
+72.748 
—41.456 
+60.008 



Here it is seen that air once breathed may contain, per 
cubic foot, from 91 to 96 cubic inches less oxygen, more 
than 70 cubic inches increase in carbon dioxide and, if the 
air is dry, some 90 cubic inches more of moisture. The oxy- 
gen has been decreased from a volume per cent of 20.94 to 
one of about 15.39, thus leaving it only three-fourths as 
rich in its essential food element. This reduction of the 
oxygen content of the air, first by the direct consumption 
of it and, second, by its dilution through the addition of 
other ingredients and by expansion due to rise in temper- 
ature, must be the main change which reduces its sustain- 
ing power. Indeed breathing becomes difficult so soon as 



Composition of Once Breathed Air. 



15 



the volume per cent of oxygen in the air has fallen as low 

as 13, so that breathing the air but twice would carry the 

volume per cent of oxygen below 

this limit, indeed as low as 10 per 

cent if no fresh air were added JHili^A^ 

to it. 

We have seen with what dimin- 
ished brilliancy a magnesium rib- 
bon burns in air once breathed. 
Here is perhaps a more convincing 
concrete demonstration of the loss 
of power to support combustion 
and to sustain bodily functions 
which characaterizes respired air. 





Fig. 10. — Caudle extinguished 
in air once breatlied. 

Using again the two-quart Mason 
jar, Fig. 9, let a lighted candle be 
lowered into it. It burns with 
scarcely diminished intensity, as 
did the ribbon, for down- going 
and up-going currents maintain a 
continuous fresh air supply. Now 
while the candle is yet burning let 
a gentle stream of air from the 
lungs be conveyed to the bottom 
of the jar, Fig. 10. Gradually, as 
the jar fills, the flame loses in 
brilliancy and finally is extin- 
guished. The flame in this case is certainly not blown out 
by the air current for the candle may be relighted and again 



Fig. 9. 



-Candle burning in 
pure air. 



16 



Ventilation. 



lowered into the jar after removing the tube. The respired 
air is heavy enough to remain and, as the candle is lowered 

into it, it will be extinguished, 
even after the lapse' of more than 
two minutes if the air in the room 
is still. 

Once more let the candle be 
lighted and lowered into the jar, 
Fig. 11. Gradually raise the' can- 
dle as the flame shows signs of go- 
ing out. Observe that the respired 
air tends to remain at the bottom, 
as may be proven by repeatedly 
lowering the candle, observing that 
as this is done the flame tends to 




Fig, 11. — The respired air 
tends to remain at the 
bottom. 

become extinguished. As the air 
is forced continually into the jar 
it becomes gradually filled and the 
lighted candle has taken the posi- 
tion represented in Fig. 12. But 
even here, if breathing into the 
jar is continued, the flame will be 
extinguished as the out-coming re- 
spired air surrounds the candle 
and shuts off a fresh supply from 
the flame. Clearly, then, air once Fig. is.-jhe flame is extin- 

*; ' ' . guished even when held 

breathed is not suitable for respir- above the mouth of the jar. 
ation unless much diluted with pure air. 




Continuous Flow of Air is Necessary. 



17 



A CONTINUOUS FLOW OF AIR IS NECESSARY. 



Since once-breathed air is not suitable for respiration 
until much diluted with that which is pure it follows that 
into and out of dwellings, schools, churches and stables, so 
long as they are occupied, must be maintained a sufficient 
and continuous flow of air to bear away that whose food 
value has been reduced and to restore an equal volume of 
that which is pure. Let us again use the two-quart Mason 
jar. Fig. 9, for another demon- 
stration. With the candle resting 
on the bottom and the mouth of 
the jar unobstructed the flame 
burns with a steady uniform bril- 
liancy. By holding the hand above 
its mouth a strong ascending cur- 
rent may be distinctly felt, but 
such a continuous up-going cur- 
rent of air from out the jar can 
only be possible when an equal 
counter current is maintained and 
it is this which sustains the flow. 

Now, with the candle still burn- 
ing in the jar let these in-going 
and out-going currents be com- 
pletely stopped by screwing in 
place the cover of the jar, Fig. 13. 
With watch in hand it will be 
found that in even less than 30 
seconds the flame is extinguished. ^quart^s~of^air^?xtfngSishIs 
Thus it is demonstrated that an "^^^^ ^^ ^^ seconds. 
ordinary candle' spoils for its own use a full gallon of 
air per minute ; 60 gallons per hour ; and more than 
200 cubic feet per^day. Twenty- four such candles would 
vitiate the air of a room for themselves and for you at the 
rate of 200 cubic feet per hour. The small portable kero- 
sene oil stove so frequently used to warm rooms demands 




18 Ventilation. 

more air than twenty-four candles and hence the rate of 
change in the room for such conditions must much exceed 
an hourly flow of 200 cubic feet, which is more than 33 
cubic feet per minute. As the candle in the Mason jar ex- 
tinguished itself in 30 seconds where the walls were abso- 
lutely air-tight it is clear that in every room and in every 
stable there must be either unintentional leaks for air to 
enter and escape or else definitely provided openings ; other- 
wise neither lights nor life could be long maintained. 

Fortunately for mankind and for his domestic animals it 
has not been practicable to build either dwellings or stables 
even approximately approaching the degree of impenetra- 
bility for air possessed by the Mason jar. But both poorly 
lighted basement dwellings and stables and the old prison 
walls and dungeon cells have come dangerously near this 
limit. Air has entered and left dwellings and stables 
through openings formed by loosely fitting doors and win- 
dows, and in varying degrees under the pressure of the 
wind through the walls themselves. Then too, the oldtime 
fireplace, the kitchen range and the heating stove have 
served a sanitary mission of the greatest importance in that 
they have always compelled a more or less continuous in- 
flow to dwellings of so much fresh air as equalled the out- 
go through the chimney. But the fireplace, for continuous 
service, has long since passed. Heating stoves are being re- 
placed by hot water and steam radiators and the air which 
warms these misses entirely the life-giving functions for it 
enters only the basement rooms, leaving by the furnace flue, 
no part of it having served the purpose of ventilation. 
Even the kitchen stove is being displaced by the oil, gas or 
gasolene range, deadly from the standpoint of pure air, for 
they tend simply to revolve large volumes of the air. of the 
room over and over, consuming its oxygen and adding to 
it all of the products of combustion, for ouly rarely are 
they connected with a chimney. 

It is of the highest sanitary importance too, in its bear- 
ing upon the general health and bodily vigor of the future, 
to recognize that in the passing of lumber as a building 



Definite Provision for Air Movement. 19 

material and in the substitution therefor of masonry, metal 
and various filled and painted compositions, both for out-' 
side and inside finish of dwellings and stables, we are stead- 
ily, surely and rapidly approaching the ability of the fruit 
jar to exclude fresh air, compelling it to enter only through 
unavoidable leaks about doors and windows. We are even 
huilding flats with wdndows and doors limited to but one or 
at most two sides, at the same time piling one over another 
where the exhausted, fouled and heated air must rise from 
one to another through ceilings, floor and hallways. The 
increasing cost of fuel too is leading to the adoption of 
storm windows and doors for the few provided, to more ef- 
fectually shut out the wind. It is difficult to imagine more 
Tinsanitary conditions from the ^' fresh air" standpoint than 
must be associated with a poorly lighted stack of over- 
crowded flats piled one above another, warmed with steam 
or hot water, the cooking and lighting done with gas. "When 
everj^ adult needs hourly, as food, scarcely less than 18 
cubic feet of the purest air to be found out of doors ; when we 
are making such strenuous efforts to shut this air out of our 
homes and stables ; when so little specific provision is being 
made to supply air to them at an adequate rate ; should we 
not be surprised rather that the dread ' ' Avhite plague ' ' does 
not take even more, vast as the number now is. And if we 
shall ever be successful in driving it from among us must 
not the battle be waged in every home where the children 
are yet well and strong, by applying continuously and ef- 
ficiently the ' ' fresh air treatment, ' ' not leaving it to be ad- 
ministered only at the hospital and to those already 
stricken ? 



PRESH AIR SUPPLY CERTAIN TO BE INADEQUATE AT TIMES IP 
DEFINITE PROVISION FOR IT IS NOT MADE. . 

Where numbers of individuals are sheltered in compart- 
ments of reasonable volume and so constructed as to permit 
of economic warming in severe weather there are certain 
to be times when the fresh air supply will be inadequate 



20 Ventilation. 

unless definite provision for such supply is made. Let us 
again have recourse to positive concrete demonstration. 
Here is a cylindrical metal chamber, Fig. 14, 18 inches in 
diameter and 20 inches deep having a cover which seals the 
chamber air-tight by means of its rim dipping under sweet 
oil carried in a groove formed about the top. Around the 




Fig. 14.— A ventilation chamber for observing the effects of inadequate 

change of air. 

sides are arranged a series of six openings each. .71 inch 
in diameter, which may be closed by means of screw-caps ; 
and two air-tight observation windows of glass. In the 
cover is a ventilation opening over which may be screwed 
a short ventilating shaft beginning at the cover, or an- 
other long enough to withdraw air from near the bottom. 
Inside the chamber is placed a lighted kerosene lamp with 
a No. 1 burner carrying a five-eighths inch wick, and turned 
up until, in an abundant supply of air, it burns kerosene 
at the rate of 13.783 grams per hour or .109 gallons per 
day. With this apparatus the following results were ob- 
tained : 

(1) With this ventilation chamber in the still air of a 
room, with the cover on but not sealed with oil; with the 
ventilator closed and with the six windows open, each pro- 



Experimental Ventilation Chamber, 21 

vided with a thin muslin screen possessing a pore space 
through which air may pass equal to 29 . 36 per cent of the 
total area, it was found that in two minutes the flame 
dropped from full height to below the top of the shield of 
the burner, and went out at the end of 11.5 minutes. 
Here we have the conditions of a steam or hot water-heated 
room provided with six open but screened windows, in 
which the lamp could burn but 11.5 minutes. 

(2) With the six windows open but screened; with the 
ventilating shaft in place, open and drawing air from the 
floor level, the flame dropped below the top of the shield 
in 6 minutes and was extinguished in 23.5 minutes. Here 
we have ample opportunity for air to escape from the room 
but inadequate entrance capacity. 

(3) With the six windows open but screened; with the 
ventilating shaft in place but drawing air from the ceiling, 
the flame fell below the top of the shield at the end of 9 
and was extinguished at the end of 27 minutes. In this 
case, with the hottest air at the ceiling and able to enter the 
ventilating shaft at that level, a stronger draft was pro- 
duced, compelling a larger supply to enter through the- 
window screens. ^ 

(4) With all of the conditions the same as in (3) except 
that the muslin was removed from one window, in 16 min- 
utes tlie flame fell below the top of the shield but at the 
end of two hours was still burning, showing no signs of 
going out. In this case the hottest air is able to fill the ven- 
tilator and with the same difference of pressure but with 
one window entirely free more air may be drawn in in a 
unit of time, the amount being barely sufficient to maintain 
a small flame. 

(5) When an 8-inch electric fan was so placed as to 
throw a strong current of air directly across the top of the 
ventilator, but with no direct current against the windows, 
the small flame being maintained under the conditions of 
(4) was in one minute increased in size to its normal free 
air dimensions. Here we have flve windows screened, one 
window open, and a strong wind blowing across the top of 



22 



Ventilation. 



the ventilator, the wind increasing the draft until the cham- 
her is sufficiently ventilated to meet the needs of the lamp. 

( 6 ) With the fan still run- 
ning and unchanged in posi- 
tion with but the ventilator 
closed the flame in 6 minutes 
fell below the shield on the 
burner and at the end of 16 
minutes had extinguished it- 
self. With the strong wind 
blowing over the top of the 
chamber, with the six win- 
dows open and five of them 
screened, but without an ac- 
tive ventilating shaft, an in- 
adequate supply of air was 
provided. 

In Fig. 16 are shown the 
rslative dimensions of the 
flame under the five condi- 
tions stated by the corre- 
sponding legend. 
In these trials the wind blew directly against the windows 
and sides of the chamber and the air movement was meas- 
ured with a delicate air meter. 

In another demonstration a silver-laced Wyandotte roos- 
ter weighing 5 . 5 pounds was substituted for the lamp in the 
chamber of Fig. 14. The ventilator and five windows were 
closed, the other screened with muslin. Under these con- 
ditions and surrounded by an air temperature of 60° F. at 
the end of 5.5 hours the bird was in distress, breathing 
lieavily, gasping with each inspiration. At this stage the 
six windows were all opened but covered with the screens 
and 2.5 hours later the bird was still breathing even more 
heavily and with greater distress. The ventilator in the 
cover was then opened but covered with a screen. After 
10 hours there had been perhaps a little improvement, if so 
it was very slight. The screens were then all removed from 




15. — Wind across ventilator 
increases draft. 



Effects of Insufficient Ventilation. 



23^ 



windows and ventilator and at the end of 2 hours the roos- 
ter was standing up apparently comfortable and breathing 
normally, presumably he was getting air sufficient to meet 
his needs. It should be observed, however, that in this case 
special provision is made for both incoming and outgoing^ 
currents. 

VARIATION IN THE SIZE OF FLAMES UNDER PERFECT 
AND IMPERFECT VENTILATION 



r 



....1- 




1. Windows all open; wind 7.39 miles per hour; 

ventilator at top. 

2. Windows all open; air still; ventilator at top. 

3. Windows all open; air still; ventilator closed. 

4. Screens on all windows; wind 10.97 miles per 

hour; ventilator closed. 

5. Screens on all windows; wind 3.26 miles per 

hour; ventilator closed. 

Fig. 16. — Here are represented five sizes of flames, natural size, as they 
"vrere maintained nnder the ventilation conditions named in Nos. 1, 3, 
3, 4:, 5, the burner being that of the lamp and the chamber the same- 
as shovrn in Fig. 14. 

A hen "of the same breed weighing 4 . 5 pounds, placed in^ 
the same chamber with all openings closed, became severely 
distressed for want of ventilation at the end of 4 hours, 13 
minutes and died from the effects 4 minutes later. In this 
case the cover was sealed with oil and corresponds with the 
trial with the candle in the two-quart Mason jar, Fig. 13, 
which extinguished itself in 30 seconds, the chamber having- 
44 times the capacity of the two-quart jar. The candle was^ 



"24 Ventilation. 

breathing in 115.5 cu. in. of air and died in 30 sec, using 
-3 . 85 cu. in. per sec. ; the hen was breathing in 5,089 cu. in. 
and died in 15,420 sec, using but . 33 cu. in. per sec. 

SERIOUS EFFECTS FOLLOW INSUFFICIENT VENTILATION. 

In the demonstrations made with the ventilation cham- 
ber referred to in the last section (Figs. 14 and 15) it was 
made clear that as the ventilation became less and less per- 
fect the size of the flame of the lamp was reduced until in 
the end it was no longer able to maintain itself. So, too, 
must it be with the functional activities of the body. The 
processes and conditions which maintained the flame of the 
lamp are identical in principle with those which maintain 
the functional activities of the various organs of the body. 
The rate of the carrying of oxygen to the flame and that of 
the bearing away of the products of combustion determined 
its size and the intensity of the heat and light generated by 
it, these decreasing from 1 through 2, 3 and 4 to 5 as the air 
movement through the chamber became less rapid, and so it 
must be with those functional activities within the animal 
body which constitute the sum total of its life ; these must 
decrease in intensity or magnitude of activity just in pro- 
portion as the life-giving oxygen is borne to, and the waste 
products are carried away from them. 

Blood passing through the active tissues is fully vitalized 
only when it is doubly charged, first, with the oxygen from 
the air breathed and, second, with the other nutrients eaten 
and drank. Neither can be efficient except as the other is 
present, ample and effective. The lamp, under the condi- 
tions of 5 had an abundance of oil, the wick was full, the 
temperature right but the oxygen was deficient. There 
could be no larger product in the form of flame except as 
the oxygen supply was made continuously larger. The con- 
ditions for activity in the body tissues are no less rigid; 
they are of the same type. It requires more oats and more 
liay to maintain day after day a team turning two 18-inch 
furrows than it does another turning two of 12, and pro- 



Serious Effects of Insufficient Ventilation, 25 

portionately more air must be taken in. If you increase 
the daily ration of grain and hay with a view of doubling 
the output of milk there is no other possibility for the herd 
than for it to charge its blood with enough more oxygen to 
make the extra product. If the herd is in the free air of a 
pasture it will do this easily, automatically and with cer- 
tainty, but if it is in a stable and that stable has a wholly 
inadequate air movement through it ; if the quality of the 
air in it is to that of the pasture as is the air in the ventila- 
tion chamber (Fig. 16) under the conditions of 3, 4 or 5 
to those of 1, then the herd will be helpless to help you and 
a, menace to those who use its product. 

The extremely serious aspect of inadequate ventilation 
results not so much from its effects in diminishing func- 
tional activities and in depressing the vital powers in their 
ability to do useful work as in its tendency to derange the 
order of chemical processes in the body leading to the for- 
mation and accumulation of products in the tissues which 
render the individual w^hose functions are so disturbed pe- 
culiarly liable to disease and especially to those of zymotic 
or contagious types, such as cholera, smallpox, diphtheria 
and tuberculosis. This world is marvelously full of germs 
of unnumbered kinds and possibilities. Let a fire sweep 
away any forest, no matter how dense or how many cen- 
turies old, with the first rain and genial sun there springs 
out from the ashes, upon almost every square inch of sur- 
face laid bare, some plant from seeds, perhaps of a hun- 
dred kinds, wafted thither by the winds, floated on the 
waters, brought by the birds or dropped by former occu- 
pants of the soil; seeds which have laid dormant perhaps 
many years or which have been resown a thousand times, 
waiting the moment when the forest should lose its mas- 
tery over the soil. Nature has neither empty places, idle 
moments nor neglected opportunities where the conditions 
for life exist. Everywhere out of the weak, out of the dy- 
ing and out of the dead, as well as out of the soil and out 
of water, life is springing. Eternally is somebody waiting 
for everybody's shoes, for all life is a competitive struggle, 



26 Ventilation. 

continuous, intense, and hence inadequate ventilation or 
anything which interferes with the normal action of the 
body, causing weakness, becomes an entering wedge, open- 
ing out an opportunity for the attack of some disease pro- 
ducing germ. 

Plant any seed in a too cold, over- wet, insufficiently ven- 
tilated soil and it at once absorbs water, its stored food ma- 
terials dissolve and, unless the other conditions favorable 
for germination are present, this soluble plant food will be 
at once appropriated by the many micro-organisms exist- 
ing in the soil and which are better able to thrive under the 
conditions surrounding the seed. The result is the seed is 
robbed of its stored food, its vitality becomes thereby low- 
ered and either its life is destroyed or it reaches maturity 
giving a reduced yield. Likewise we should never forget 
that in the case of our own bodies and in those of our do- 
mestic animals there is continually a struggle for mastery 
between the normal living cells which constitute the various 
organs and many lower life forms always present in the 
system as the seed are in the forest soil, simply biding their 
opportunity. Any condition, therefore, like that of an in- 
sufficient supply of pure air, insufficient or improper food 
of other kinds, which must tend to lower the vitality or 
intensity of action in the cells of any organ is likely to 
place them at the mercy of the invading germs which, like 
weeds in the field, are simply biding their time to spring 
into overmastering supremacy, thus bringing disease and 
perhaps death as the result. 

We fully appreciate that in a highly fertile soil, well 
managed, crops are less liable to disease and that they much 
more readily keep the mastery over weeds than they do on 
a poor soil or on one in bad condition, poorly managed. It 
it equally true with the organs of the animal body ; if they 
are abundantly nourished, surrounded by congenial condi- 
tions, the possibilities for contracting tuberculosis, cholera, 
smallpox or other forms of contagious diseases whose germs 
we must remember are almost always about us, no matter 
how careful we may be, are very much reduced. It is the 



Serious Effects of Insufficient Ventilation. 



27 




body starving for want of oxygen or for want of any other 
essential food material, or which is weakened in any other 
way, which is most likely to be overpowered by one or an- 
other of these foreign organisms, and a single germ may 
gain the mastery over a system in weakened condition 
where multitudes of them would be harmless within a vig- 
orous constitution, well nourished and normally cared for. 
And since the body out of which life 
has gone begins immediately to pass 
into decay it stands to reason that 
one sick or weak must be more liable 
to suffer from attack than anotheT 
who is strong, and the truth of this is 
abundantly borne out by statistics, 
particularly by those expressing the 
rate of mortality resulting from con- 
tagious disease associated with condi- 
tions of inadequate' ventilation. 

As a concrete illustration of the 
manner in which insufficient air may 
alter the nature of chemical changes 

let this lamp, Fig. 17, be' used, which 
is burning with a full bright flame 
under the influence of a strong cur- 
rent of air. The moment this cur- 
rent is cut down by holding the hand 
under the draft. Fig. 18, the chimney 
fills with a sooty flame and smoke. 
There is not encfugh oxygen carried 
by the reduced current to unite with 
both the hydrogen and the carbon of 
the kerosene and, as the hydrogen 
Pig. i8.-Lamp burning ^^s a strougcr attraction than the 
with insufficient sup- carbon for oxygcu, it appropriates so 

ply of air resulting iti x-r-jr. 

in smoky flame. nearly the whole that a portion of thef 

carbon is set free in the form of smoke. There is thus formed 

a waste product abnormal to the lamp in healthful operation 

and if allowed to continue would ultimately clog the chim- 
3 



Fig. 17. — L<amp burning 
with full supply of 
air, without smoke. 




28 Ventilation. 

ney through deposits on the waU, thus extinguishing the 
flame by entirely shutting off the air supply. Insufficient 
ventilation may in like manner result in abnormal chem- 
ical processes in the body, giving rise to products which if 
allowed to accumulate in the system become positively in- 
jurious. It is of course not intended to convey the impres- 
sion that if respiration is compelled to go on in an insuf- 
ficient supply of oxygen carbon will be deposited in 
the tissues, as soot was deposited on the chimney, but there 
are good reasons for thinking, indeed direct observations 
show, that when there is an insufficient supply of oxygen 
in the air breathed, as when the carbonic acid content is 
abnormally high, materially less carbon dioxide is thrown 
off. In the experiments with the fowls cited there aecumu- ' 
lated in the ventilation chamber a very large amount of 
moisture, enough not only to wet the walls so that it ran 
down the sides but to so saturate a layer of dry sand which 
was used as an absorbent as to cause the surface to appear 
wet. 

In April, 1891, we conducted, during 14 days, an experi- 
mental study of the effect of ample and deficient ventilation 
upon 20 milch cows. The experiment was made in a half- 
basement stable, represented in Fig. 19, having three out- 
side doors, thirteen large windows and a door leading by 
a stairway to the floor above. The ceiling was nine feet 
above the floor and the stable contained 960 cubic feet of 
space per cow. Leading upward from the ceiling there were 
two hay chutes 2 by 3 feet in cross section, 20 feet high, 
which could be open*ed or closed at will, and a ventilating 
flue, 12 by 16 inches, terminating near the ridge of the 
roof inside. The experiment consisted in closing all doors 
and windows and the two hay chutes, leaving only the ven- 
tilating shaft open, for the trials under insufficient ventila- 
tion ; and in leaving both hay chutes open, together with the 
ventilating flue, for good ventilation. 

During the trial the cows were kept continuously in the 
stable, with the hay chutes closed during two days and then 
with tliem open two days, the trials being repeated four 



Ventilation Experiment with Cows. 



29 



times. Following these four trials the hay chutes were 
closed during three consecutive days for poor ventilation 
and left open the following three, making 14 days in all. 
The feed eaten, the water drank, the milk produced and the 







Fig. 19.— stable in which ventilation experiment was conducted. One or 
more hay chutes, with no ventilating flue, has been a common way of 
ventilating dairy stables; often the chutes are absent. 

COWS themselves were weighed each day. It was found 
that measurably the same amount of feed was eaten under 
both conditions of ventilation. But during the days of in- 
sufficient ventilation the cows drank, on the average, 11.4 
pounds more water each daily and yet lost in weight an 
average of 10.7 pounds at the end of each period, regain- 
ing this when good ventilation was restored, and this too 
when they were drinking less water. During the good ven- 
tilation days too, for each and every period, the cows gave 
more milk, the average being . 55 pounds per head per day. 



30 Ventilation. 

At the end of the 14 days the cows were turned into the 
yard and exhibited an intense desire to scratch and lick 
their sides and limbs, doing so until the hair in many cases 
was stained with blood. Examination showed that during 
the interval a rash had developed which could be felt by 
the hand in the form of hard raised points and the rasping 
of these off caused the bleeding. In the case of these cows 
it seems clear that on the days of insufficient ventilation 
conditions existed which may fairly be compared with those 
causing the smoking in the lamp ; the reduced supply of air 
in the stable made it impossible for entirely normal chem- 
ical changes to take place in the body ; it was impossible for 
the lungs to remove the waste products in the form of car- 
bon dioxide to as great an extent as was usual and it seems 
highly probable that because of this some of the waste prod- 
ucts had to be of a different chemical nature, such as could 
be eliminated through other channels. But if this was true 
a stronger action on the part of the kidneys and perhaps 
on the part of the alimentary canal as well, which created 
the increased demand for more water to^the extent of 11.4 
pounds daily, all of which was lost and enough additional 
to reduce the average weight 10.7 pounds by the close of 
each period, would seem to justify the conclusion, not only 
that abnormal chemical changes were taking place in the 
bodies of the animals, but also that the elimination of im- 
purities so produced was not occurring in the usual way.' 
During the days of insufficient ventilation moisture con- 
densed to such an extent on the walls and ceiling as to drip 
and run down the sides ; at the same time the odor was very 
strong and the air depressing to one coming in from out- 
side. 

It is important to point out here that the appointments 
of the stable in which these trials were conducted are typi- 
cal of perhaps a majority of dairy stables in the United 
States today ; furthermore, it is a very common practice to 
close hay chutes and similar openings during cold weather, 
especially during the night, thus establishing the precise 
conditions designated in this experiment as poor ventila- 



Volume of Air Movement Needful. 31 

tion and which produced the observed results. The damp- 
ness in the stable due to condensation of moisture, the of- 
f ensive odors and the oppressive character of f he air which 
have been referred to as occurring in the experiment de- 
scribed are all present in the average dairy stable in greater 
or less intensity wherever ample provision is not definitely 
made to secure proper ventilation. 

VOLUME OF AIR WHICH SHOULD MOVE CONTINUOUSLY 
THROUHG DWELLINGS AND STABLES. 

''Jane, you and Ellen go up and do the chamber work 
and be sure to open the windows and give the rooms a good 
airing." Yes, indeed, but why not a better airing during 
all the night when the sleepers are occupying the beds. 
Certainly a refreshing drink direct from the spring, and a 
full supper from the dining room, easily satisfy all crav- 
ings from an early to bed to a late to rise. And will not 
a full breath or at least a half hour of them, when drawn 
from the park or from the pasture, as fully meet the needs 
of a night? Perhaps Mother's caution does imply this or 
was it her remembrance of a weary waking from an unre- 
f reshing sleep ; a mother 's feeling that something surely 
ought to be done and she would faithfully do the little that 
lay in her power? Or is the idea really prevalent that to 
have the chamber full of outdoor air to start with will gen- 
erally meet the requirements of the night ? 

It is difficult for many, and perhaps for most people, to 
harmonize their own experience in this matter of ventila- 
tion with those who advocate the imperative need of special 
provision to secure ventilation, as it seems clear that since 
no such provisions are generally made for either dwellings 
or sj;ables and since no serious consequences have certainly 
resulted which are ascribed to the lack of such provisions 
they can hardly be regarded as necessary. For all such let 
them be urged to reflect that the animal mechanism posses- 
ses a marvelous power of endurance and for the tolerance 
of conditions even seriously injurious and that usually the 



32 Ventilation. 

existence of such pending troubles are not recognized until 
it is too late and that even when they are recognized their 
true cause may remain unknown. Above all should it be 
emphasized and ever borne in mind that there is an ex- 
tremely wide range in the powers of endurance of foul air, 
not only among different animals, but among individuals 
of the same species, so that wherever more than one is oc- 
cupying a compartment the degree of air purity must cer- 
tainly be such as to meet the needs of the least tolerant oc- 
cupant. Not only does the lung capacity of individuals 
vary but the depth of respiration is very different owing 
to difference in habit or difference in dress, thus making it 
impossible for all to derive the same amount of oxygen, or 
eliminate the same amount of carbon dioxide under like 
conditions of air. Such differences are of course exag- 
gerated in all cases where the lung capacity is reduced on 
account of disease. 

When the breath is forced into a cold lamp chimney or 
glass vessel there is at once perceptible a marked condensa- 
tion of moisture on the walls, showing that very material 
quantities of moisture are being discharged in invisible 
form into ,the air. So too, if the hand is placed for a sec- 
ond with the palm against the cold surface of a mirror 
and removed before the surface has been warmed there will 
be apparent in this case also a marked condensation of 
moisture, shovvdng that not only from the lungs but from 
the skin as well the air of compartments is being contin- 
ually charged with moisture. In the case of man the mean 
amount of moisture exhaled from the lungs and transpired 
by the skin is placed by Seguin at 1,080 grains per hour, 
the minimum being 486 and the maximum, except under 
very unusual conditions, 1,458 grains per hour. This 
moisture discharged into the air of a compartment in which 
no change is taking place tends rapidly to saturate it, soon 
bringing it to a point where moisture condenses on the 
walls. If we would not have this moisture condensation 
there must necessarily be a movement of air through the 



Removal of Perspired and Exhaled Moisture, 33 



room sufficient in volume to carry away the moisture as 
rapidly as it is formed. 

The ability of air to carry moisture under given condi- 
tions of temperature and pressure is very definitely known ; 
hence it becomes possible to compute the volume of air 
which must pass through any compartment where a known 
amount of moisture is being thrown into the air, in order 
that this moisture may be carried away as rapidly as 
formed. The following table has been computed from Se- 
guin's data, using the Smithsonian table 167 giving the 
capacity of air for moisture. 

Volume of air 75 per cent saturated at 40°, 50°, 60°, and 70° F. re- 
quired when leamng the room saturated at 70°, to remove the mini- 
mum, average and maximum amount of moisture throicn off from the 
lungs and skin per hour, hy man. 



Minimum 
Average. . . 
Maxtmum^ 



When the temperature of the incoming air is, 

40° 50° 60° 70° 

The reauired hourly movement of air is. 




244 
541 
731 



From this table it is seen that in order to remove from 
a compartment the moisture thrown into its air as invisible 
vapor from the lungs and skin, so as to avoid oversatura- 
tion, there must be moved through it each hour more than 
185 cubic feet, 220, 294 or 541 cubic feet on the average for 
each occupant, according as the air enters at 40°, 50°, 60° 
or 70° F., the air at the same time passing out fully sat- 
urated at 70°. It is clear, therefore, in order that dwellings 
and especially schoolhouses, churches and stables may have 
a reasonably dry atmosphere there must be a large and con- 
tinuous air movement through them which is proportioned 
to the number of occupants. 

From the recent studies of Dr. Armsby it was determined 
that a 1,000-pound steer charges the air of the stable with 



34 



Ventilation. 



invisible vapor, from skin and lungs, to the extent of no 
less tlian 10.4 pounds daily. In order, therefore, that a 
dairy stable of twenty cows may not have the moisture con- 
densed on its walls there must be an air movement through 
. it continuously sufficient to remove 208 pounds daily ; for 
40 cows it must be sufficient to remove 416 pounds ; for 60, 
624 pounds; for 80, 832 pounds and for 100 cows there 
must be a movement which will carry from the stable 
through the out-going air, as invisible vapor, 1,040 pounds, 
or more than half a ton, of moisture daily. The mean 
amount of moisture carried by the air in most parts of the 
United States at 7 A. M. is seldom less than 70 per cent of 
its full saturation capacity. In the next table there are 
given the volumes of air per hour and per cow which must 
pass through a stable in order to prevent condensation. 

Required number of cubic feet of air, per hour and per head, to pre- 
terit condensation of moisture when it enters the stable 75 per cent, 
saturated a7id leares it saturated at the stable temperature. 



If the outside air is 
75 per cent saturated 
at the temp, of 


When the stable temperature is, 

80° 40° 50°- 60° 70° 

The volume of air per head and per hour must be, 


—10° F 


cu. ft. 
1,788 
1,982 
2.334 
2.620 
3.140 
6,228 


cu. ft. 
1.164 
i;253 
1,385 
1,489 
1.634 
2,201 
4.268 


cu. ft. 

792 

832 

887 

931 

996 

1,165 

1,566 

1.782 


cu. ft. 
540 
554 
569 
614 
638 
715 
842 
1.126 


cu. ft. 
394 


0° 


402 


10° 

15° 


415 
424 


20° 


434 


30° 


466 


40° 


520 


50° 




655 











This table makes it clear that in dairy stables a large and 
continuous movement of air through them is imperative 
simply to prevent the condensation on the walls of the 
moisture of perspiration and respiration ; and the damp- 
ness so often observed in basement stables is a proof posi- 
tive of the too slow rate of change of air in them to even 
carry out the moisture. When the outside air containing 
three-fourths of all the moisture it can retain at a tem- 
perature of 0° enters a stable which is maintained at 70° 
F., then 402 cubic feet per cow must enter and leave the 



Volume of Air Required to Remove Moisture. 35 

stable each hour to completely remove all the moisture 
thrown off by the skin and lungs. If the stable tempera- 
ture is maintained at 60° instead of at 70° then the air move- 
ment must be at the rate of 554 cubic feet; if at 50°, 832 
cubic feet; if at 40°, 1,253 cubic feet, and if the stable 
temperature is as low as 30° then, with the air entering the 
stable three-fourths saturated at 0°, no less than 1,982 
cubic feet of air must enter and leave the stable for each 
cow each hour. And so if the outside air is three-fourths 
saturated at 20° and the stable temperature is maintained 
at 70°, the necessary air movement, to keep the stable dry, 
is 434 cubic feet per hour and per cow; but if the stable 
temperature is 60° then the amount must be 638 cubic 
feet; if 50°, then 996 cubic feet; if 40°, then 1,634 cubic 
feet ; while if the stable is as cold as 30° then the air change 
must be at a rate exceeding 3,140 cubic feet per hour and 
per cow to carry away the moisture thrown off. These last 
statements mean that when 20 cows are housed in a stable 
with a floor space 20 by 40 feet and with 9 foot ceiling this 
entire volume of air must be changed once every 50 minutes 
when the stable temperature is 70° ; once every 33 minutes 
when the temperature is at 60° once every 21 minutes if it 
is at 50° once every 13 minutes if it is at 40° and if the 
stable temperature is as low as 30° then the entire volume 
of air in the stable must be changed as often as every 7 
minutes in order to prevent moisture condensation. It is 
thus seen that the lower the temperature of the stable and 
the higher the temperature of the outside air before enter- 
ing the stable the larger must be the air movement through 
it in order to carry away all the moisture exhaled by the 
animals. 

But large as must be the air movement through stables 
simply to keep them dry this is not sufficient to maintain 
the required purity of air to meet the needs of the animals 
themselves either in the oxygen supply or in the removal of 
carbon dioxide and the poisonous volatile organic products 
exhaled by them. It must be held of the highest import- 
ance, from the standpoint of house and stable sanitation, 



36 Ventilation. 

that some standard of air purity should be experimentally 
determined so that the rate of air supply for each individ- 
ual, which constitutes adequate ventilation, shall be def- 
initely known and shall be used in house and stable con- 
struction in making definite provision for adequate ventila- 
tion. 

De Chaumont has assumed a standard of purity of air for 
man of 99.51 per cent, which means that the carbon dioxide 
in the air of a room due to respiration should not be aug- 
mented more than two parts in ten thousand over that car- 
ried by pure air, or more than .02 volume per cent. This 
limit, too, is found by direct observation to be that at which 
the sense of smell fails to detect the odor of * ' closeness ' ' in 
an occupied room. Carnelly, Haldane and Anderson admit 
a standard of purity much lower than this and it is com- 
monly held that, for man, when the air of a room contains 
no more than .07 volume per cent of carbon dioxide it is 
sufficiently pure for the purposes of respiration. In using 
the carbon dioxide as a standard it is held by writers on 
ventilation, not that more or less of this would be injurious, 
but rather that this amount of carbon dioxide is an index 
of the degree at which the ''crowd poisons" have become 
sufficiently concentrated to be injurious. We feel that it 
may quite as likely express the degree of oxygen-exhaus- 
tion at which the more sensitive occupants of a room begin 
to feel the depressing effect of an insufficient supply of 
oxygen in the system, and the time at which deeper breath- 
ing needful to compensate for exhaustion becomes a con- 
scious effort. De Chaumont 's standard of purity requires 
an air movement of one cubic foot per second for each adult 
man when at rest, or 3,600 cubic feet per hour. Men in 
active labor would require more, while women and children 
at rest would need somewhat less. The other standard of 
purity would require an air movement of about 1,800 cubic 
feet per hour for an adult man at rest and would hold the 
composition of the air of the room at 99 parts pure and 
one part at the degree of exhaustion of once-respired air, 
and in this condition its oxygen content would be reduced 



Leakage of Air Through StaMe Walls. 37 

from 20.582 volume per cent, as stated in the table for 
moist air, page 13, to 20.529 per cent, an exhaustion of its 
oxygen content amounting to .05 volume per cent of the air 
and of .26 per cent of the oxygen itself. De Chaumont's 
standard of purity would permit exhaustion to but one half 
of these amounts. 

In dealing in a practical way with problems of ventila- 
tion, providing means for the entrance into and exit of air 
from dwellings and stables, it is necessary to take into ac- 
count the openness of structure which is unavoidable under 
present methods and materials of construction, for the rea- 
son that in consequence of this openness of structure there 
results a not inconsiderable air movement into and out of 
compartments through openings not intentionally provided, 
and which does much toward providing the necessary air 
supply, even when the wind movement outside is small .. 
That material changes of air do take place through the 
walls of buildings we have abundant proof, and experi- 
ments conducted at the Geneva Experiment Station, N. Y. 
furnish a basis for computing what this rate of movement 
was under one set of conditions. The stable in question had: 
a floor space of 51 by 33 feet with a 9 foot ceiling, accom- 
modating at the time 22 cows. Doctor Jordan was having 
a study made of the distribution of carbon dioxide in the 
stable air and during one set of observations, when the 
ventilators were open, the mean content of carbon dioxide 
was found to be .462 volume per cent, .534 per cent near 
the ceiling, .501 at a middle level and .351 near the floor. 
If we may take the composition of once-respired air in this 
case at the value given in the second part of the table, page 
14, and the amount of air breathed per hour and per cow at 
116.8 cubic feet, page 9, the degree' of purity of air in 
this stable must have been at the time 89.72 per cent and 
air must have been entering and leaving it at the rate of 
some 24,995 cubic feet per hour, or 1,136 cubic feet per cow. 
When the ventilators of this stable were closed, however, 
the carbon dioxide present in the air had increased so as to 
be 1.40 volume per cent near the ceiling, 1:236 per cent at 



38 Ventilation. 

a middle level and 1.03-i per cent near the floor, making an 
average of 1.2233 volume per cent. On the same basis of 
calculation as used above air in this case must have been 
entering and leaving the stable at a rate of some 9,059 cubic 
feet per hour, which is nearly 412 cubic feet per cow, and 
the air in the stable at this time had a degree of purity ap- 
proximating 71.63 per cent, which means a reduction of 
the oxygen content to 19 . 13 volume per cent, a lowering be- 
low that of standard air of 1.36 per cent. We have, there- 
fore, in this case, a dairy stable accommodating 22 cows, 
built close for warmth and having all its special provisions 
for ventilation closed, yet with air entering and leaving it 
at the rate of more than 9,000 cubic feet per hour, the air 
being changed in the stable as often as once in every 100 
minutes, whereas, when both the intentional and uninten- 
tentional facilities for interchange of air were in operation 
the air of the stable was changed once in about every 36 
minutes. 

At the Minnesota Experiment Station experiments were 
conducted which furnish another basis for making a similar 
estimate regarding the permeability of stable walls to air. 
In this case a steer was kept during varying intervals of 
time in a closed stall having a capacity of 784 cubic feet 
with one outside wall and a single window. The stall was 
provided with a cement concrete floor, the walls were of 
hard brick and the ceiling of boards, which was covered 
with heavy muslin, this and the walls being painted to ren- 
der them more nearly air tight. The window and a door 
opening into a hallway were close fitting and the door was 
so arranged as to permit the animal to be fed and watered 
without opening the door, the animal being cared for with- 
out the attendant entering the stall except at the close of 
an experiment. Under these conditions there was a wide 
variation in the composition of the air in the stall, the data 
showing a range between .52 and 2.67 volume per cent, of 
CO2. The authors say ''After the work had been in prog- 
ress for a short time the windows, walls and ceiling became 
covered with water which at times ran down the walls and 



Leakage of Air in Minnesota Stable. 39 

drippt^d from the ceiling. The quantity varied with the 
condition of the weather. After the stall had been closed 
several days at the beginning of Series B mould began to 
appear on the walls and gradually increased until almost 
the entire wall surface was covered. After the closed stall 
was in use several weeks it was noticed that the paint was 
softened in several places on the wall and running down 
with the water. This continued until almost the entire 
wall surface was bare of paint." 

''After entering the closed stall at the close of a period 
to make a reading or remove an animal one was forcibly 
impressed by a stifling air, its excessive moisture and the 
apparently high temperature. The first few minutes one 
invariably had difficulty in breathing, this soon passed 
away, and he began to sweat, and feel uncomfortably 
warm. This condition did not last long, perhaps five min- 
utes, after which no unpleasant effects were noticed. After 
leaving the stall the outside air seemed cold and so light 
that one involuntarily took several very deep inspirations. 
The odor of manure did not become sufficiently strong to be 
offensive even at the close of a 10-day period. ' ' 

"We have here what would appear to be extreme condi- 
tions as to closeness of construction ; conditions under which 
steers were kept and fed continuously without leaving the 
stable and without having the door opened, except the slide 
through which feed was quickly introduced, for periods, 
in one case, as long as 28 days ; conditions in which the ex- 
perimenter thought the animals did not seriously suffer 
from the effects of insufficient ventilation ; but conditions 
which the experimenter himself invariably found oppres- 
sive, as he has described above, on entering the stall at the 
close of an experiment. It seems quite clear from the anal- 
yses of the stable air which were made that there must have 
been a very considerable air movement through the stable 
at all times whenever there was a considerable wind move- 
ment outside. Taking the average weight of the animals 
experimented with at 600 pounds and assuming a respiration 
volume proportional to this weight and, further, that the 



40 Ventilation. 

consumption of oxygen and excretion of carbon dioxide oc- 
curred in the normal ratio, we may calculate the air move- 
ment through this stall by the same method used in the case 
of the dairy stable. When such a calculation is made a . 52 
volume per cent of carbon dioxide maintained in the stall 
air requires a continuous flow at the rate of some 591 cubic 
feet per hour, and when the content of carbon dioxide was 
maintained at 2.61 per cent an exchange of air is required 
at a rate not less than about 112 cubic feet per hour. It 
must not be understood that the values here computed, re- 
lating either to this stall or to the dairy barn which has 
been considered, have more than an approximate degree of 
accuracy. They undoubtedly do express a general and im- 
portant truth, namely, that material volumes of air do enter 
and leave what are regarded as closely constructed dwell- 
ings and stables by means of openings not specially pro- 
vided, and that the amount of such movement varies be- 
tween extremely wide limits, as must have been the case in 
the Minnesota stall, the ventilation being best when the 
wind movement is greatest outside. It is clear however, 
from the data presented in this connection, that even under 
the best of outside conditions close stable and dwelling con- 
struction can seldom give adequate ventilation, certainly 
never at times when the air is still. 

The experiments conducted at the Minnesota Experiment 
Station lead the authors to say : ' ' Cattle seem to thrive 
under what are apparently the worst possible conditions of 
stabling. Beef cattle fatten well and dairy records are 
made in stables that are simply abominable from recognized 
standards of good stabling. * * * 

*' Stable ventilation in our northern states during our 
long cold winters is a difficult problem at best. To get any- 
thing like the amount demanded by most authorities is cer- 
tainly impracticable. If less is compatible with the health 
and comfort of our confined stock it is very important that 
we know it and be quite sure of it. If what we call moder- 
ately or even decidedly foul stable air is not commonly in- 
imical to the health and comfort of these animals or to the 



Ventilation Problem Stated. 41 

owner's profits then it is of the utmost importance that we 
know this also. * * * 

' ' The real problem with which we have to finally deal is, 
how little air is compatible with normal health and comfort 
of the stock and with economic feeding. ' ' 

It is very unfortunate that language like this should find 
a place in the instructional literature of animal husbandry 
for it is certainly much nearer the truth and conducive to 
a safer practice to say : The real problem with which we 
have finally to deal is how nearly can we maintain the air 
of dwellings and stables at the normal out-of-door fresh air 
purity with practicable economy. It has certainly never 
been a maxim of good feeders to supply the smallest ration 
*' compatible with the normal health and comfort of the 
stock and with economic feeding. ' ' Rather has it been the 
practice to place before the animals the largest amount of 
feed they can possibly be urged to eat and return a good 
profit. A like maxim must lead in the supply of air which 
constitutes more than two-thirds of every adequate ration. 

In our study of stable conditions and of the possibilities 
of air supply we have been led to the conviction that an air 
movement through the stable can and should be secured 
which will maintain a degree of purity not lower than 96.7 
per cent ; that the air of stables and dwellings should at no 
time contain more than 3.3 per cent of air once breathed. 
Such an air movement as this is entirely practicable in the 
stables of cold climates and a much higher rate is possible 
in every properly heated dwelling. 

In order that the air of a stable shall at no time contain 
more than 3.3 per cent of air once breathed it must enter 
and leave at the rate of 4,296 cubic feet per hour and per 
head for horses, at the rate of 3,542 cubic feet for cows, of 
1,392 cubic feet for swine, of 917 cubic feet for sheep and of 
35 cubic feet per hour for hens, on the average. In the case 
of man the amount of air breathed per hour is 17 . 71 cubic 
feet and the hourly movement through the dwelling and 
sleeping room, in order to maintain the degree of purity 
stated, needs to be not less than 537 cubic feet for each adult. 



42 



Ventilation. 



These several amounts are graphically represented in Figs. 
20 and 21. | 

To secure an air movement through a cow stable contain- 
ing 20 cows a ventilating flue 2 feet by 2 feet is required 
through which the air moves at the rate of 295 feet per 
minute. A flue of this size, too, will be required for 17 




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Fig. 20.— Each drawing represents the volume of air which should enter 
and leave the stable or room during each hour for each adult occu- 
pant. Each square represents a square foot and the subdivisions 
indicate the number of cubic feet in each room. 



horses, for 51 pigs and for 77 sheep. Double the number 
of animals named will require ventilating flues having 
nearly double the cross section stated while smaller num- 
bers would require flues relatively larger in proportion on 
account of the relatively greater friction in small, as com- 
pared with that in large flues. 

To emphasize, we wish again to state that it is a matter 
of the highest economic and sanitary importance that rigid 



Volume of Air Required Hourly. 



43 



experiments should he instituted, both for man and for do- 
mestic animals, which shall establish beyond all doubt what 
is an entirely sufficient degree of air purity for dwellings 
and for stables to the end that a safe basis may be had upon 
which to specifically provide proper and fully adequate 
means for ventilation. It is important to recognize that the 



V 


^^-^ 


'M 




^^--::: 




..■■■ ^^-^ 






..-'" 






— 












"'.'V 




— 






■---^^ 






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^^ \ \ \ \ 




Fig. 21.— Each drawing represents the volume of air which should enter 
and leave the stable during each hour for each adult occupant. The 
rulings indicate the number of cubic feet in each room, each square 
is one foot. 



standard of air purity here assumed is materially below 
that which admits a content of carbon dioxide in the air of 
a room of .07 volume per cent. Indeed the standard as- 
sumed for stables permits a content of carbon dioxide as 
high as . 167 volume per cent, a quantity more than double 
that above ; and it is important to say again here, for com- 
parison, that Doctor Jordan found in his stable, with the 
ventilation system in operation, a carbon dioxide content as 
high as .462 volume per cent, which is nearly three times 
that of the standard we have assumed for stables. In his 



44 Ventilation. 

case the degree of air purity was 89 . 67 volume per cent in- 
stead of 96.7 which we have assumed as a probably safe 
limit. Should it be found admissible to tolerate in a stable 
5 to 10 per cent of air once breathed, instead of 3.3 per 
cent, which is here assumed, such a degree of purity could 
be more readily secured under all conditions of weather. 
We feel that it would be unwise, however, to adopt a lower 
standard, in advance of definite knowledge, in stable con- 
struction for the reason that it is a very simple matter to 
reduce the air movement through a stable when the large 
capacity of the ventilating system causes the rate of change 
to be too high. If the capacity of the system is too small 
there is no help except that of resorting to open windows or 
similar devices which are undesirable in cold weather, par- 
ticularly if it is windy. 



PRINCIPLES OF VENTILATION. 



The installation of a satisfactory system of ventilation re- 
quires (1) The choice of a proper unit of air movement; 
(2) the application of the laws and principles governing 
air movement ; (3) and the adoption of proper construction 
with adequate motive power to insure the required supply 
of air. There can be no proper ventilation for dwelling or 
stable unless into it and out of it there is a continuous flow 
of air at some proper unit rate. It has been pointed out 
that some have adopted as this proper unit for man a cubic 
foot of air per second; that others have accepted one half 
this volume as adequate ; and that we have taken as possibly 
sufficient for the cow 3,542 cubic feet per hour. Without 
contending that either of these units is the best it must be 
insisted that some unit should he chosen and then adequate 
provision made to secure at least this amount. It should 
be recognized, too, that in increasing the air movement be- 
yond the standard chosen there is little chance that injuri- 
ous physiological effects will follow as the result of such 
choice provided a proper temperature is at the same time 
maintained. 

Unnecessary expense of installation and maintenance is 
about the only chance for mistake against which to guard; 
and in the matter of expense it should be remembered that 
where the forces which maintain the air movement through 
the ventilated space are the wind and the waste heat of oc- 
cupants or of heating and lighting appliances the cost of a 
ventilating system above the standard capacity will be only 
that required to incorporate a somewhat larger amount of 
material in its construction. It is the part of wisdom, 
therefore, to install a ventilating system whose capacity 
shall be abundantly large. 



46 Ventilation. 

The maintenance of a flow of air through a building re- 
quires the continuous expenditure of energy and the 
amount of this energy and of work done will be in direct 
proportion to the weight of air moved through the venti- 
lated space and the resistance it is necessary to overcome in 
accomplishing this movement. If the air of an audience 
room occupied by 1,000 persons is supplied at the rate of 
537 cubic feet per hour and per capita the work to be done 
is approximately that of moving some 21^ tons of air 
through the room each hour. 

If De Chaumont's standard of one cubic foot of air per 
second and per person is adopted then the amount of work 
to be done is that needed to move through the room 144^ 
tons of air. 

So, too, if a herd of 100 dairy cows is to be supplied with 
air at the rate of 3,542 cubic feet per head and per hour the 
necessary amount of work is that of moving through the 
stable each hour 14 tons,* which, if the air is forced 
through vertical shafts 40 feet in length, of ample' capac- 
ity, represents about one-half horse power. 

POWER USED IN VENTILATION. 

The motive power commonly utilized in ventilation is (1) 
the passing wind; (2) heat generated within the space to 
be ventilated by its occupants, by lights and by fires; (3) 
rotary fans driven by one or another source of power; (4) 
and steam jets or coils in ventilation flues. By whatever 
source of power the air movement for the purposes of ven- 
tilation is effected this results from a difference of pressure 
established between the air in the space to be ventilated and 
that outside, and this difference of pressure is the immedi- 



^ 537X1000 ^<^ ^ 21.48 tons 
2000 

2 3600 X 1000 X .08 

2000 

3 3542 X 100 X. 08 



2000 



= 144 tons. 
- 14.168 tons. 



Motive Power in VentUation. 47 

ate cause of air movement into and out of the ventilated 
space. 

When the wind has its progress arrested or checked by a 
building pressure is developed ; this pressure tends to force 
air through any pores, chinks or openings which may exist 
in the wall. But if air is forced into the building that in- 
side will be placed under a greater pressure and this 
greater pressure will force a flow outward on the leeward 
side or upward through any chimney or ventilating shaft 
which may exist. All are familiar with the existence of a 
much stronger current passing around the comer of a 
building on a windy day than is found at a distance be- 
yond. This higher wind velocity is proof of the increased 
pressure which has resulted from the check to its onward 
progress it has received from the building and this must 
assist in the ventilation of all buildings whose walls are not 
absolutely air tight. 

The pressure of the wind on a building, and therefore 
the ''head" which tends to force air into it, when the im- 
pact is at a right angle, has been found to be approximately 
given by the two equations 

Pressure or Head = .005 V^ or 
Pressure or Head = .00096 Y^ 
where V is the velocity of the wind in miles per hour, the 
result being in pounds per square foot of surface in the first 
equation, and in inches of water in the second. These 
equations mean that if a wind is blowing at the rate of five 
miles per hour against the walls of a dwelling or stable, 
striking them at a right angle, the pressure so developed 
tends to force air through any openings in the windward 
side with an intensity approximately equal to .125^ lb. 
per sq. ft. and equal to .024^ inch of water, the precise 
value varying with the weight of a cubic foot of air 
at the time, this changing with the temperature, pres- 
sure and composition. This amount of pressure is the- 
oretically capable of causing a flow through a smooth, 

^ 005 X 5 X 5 = .125 lbs. per sq. ft. 

2 .00096 X 5 X 5 = .024 inch water pressure, 



48 Ventilation. 

straight cylindrical ventilating shaft or chimney one square 
foot in cross-section and 40 feet high, equal to some 36,000 
cubic feet per hour. 

Then too, whenever the wind blows directly across the top 
of a chimney, ventilator or other opening it tends to pro- 
duce a suction which has the effect of reducing the pressure 
at the opening and of causing a flow outward increasing 
with the reduction of pressure. The magnitude of such 
wind action, in its tendency to produce a flow of air into 
and out of spaces needing ventilation, is given by the equa- 
tion, 

Pressure or Head = .00024Y2, 

where V is the velocity of the wind in feet per second and 
where the head or pressure is in inches of water. If the 
velocity of the air is taken in miles per hour this equation 
becomes 

Pressure or Head = . 000518 Y-. 

These equations mean that if the wind is blowing at the 
rate of five miles per hour across the top of a ventilating 
flue or chimney there would be developed a suctional effect 
or head equal to, using the second equation, 

.000518 X 5 X 5 = .01295 inch water pressure, 

and this is capable of producing, in a flue 40 feet high with 
a^cross-section of one square foot, a theoretical flow of some 
26,000 cubic feet per hour. Such theoretical velocities as 
these cannot be realized in practice because the resistances 
met with by the air in entering buildings, ventilating shafts 
or chimneys vary between wide limits; moreover if provi- 
sion is made for air to enter through thin openings in walls, 
such openings are never fully effective because of the inter- 
ference of currents entering obliquely around the margins, 
causing a contraction of the air stream which may reduce 
the theoretical flow to about 65 per cent. The manner in 
which the wind becomes a motive power in ventilation is 
indicated in Fig. 22. 



How Wind is Effective in Ventilation. 



49 



The wind has its progress arrested by the building, 
thereby compressing the air and forcing a portion of it into 
the building through any openings, as at A, while other 







, , ■;<,!.. ■.'.•:.*•-'. .- - ...,, 

3«i "IS/iSWi'*! m=/«»'i w= ►=«iwr»;»FXcgnii»i£h 



'^.SS 



Fig. 22.— Manner in which the wind becomes effective as a motive power 
in the draft of chimneys and in ventilation. 

portions are driven upward along the sides past B and over 
the roof across the top of the ventilator at C, and other por- 
tions still flow around the corners. The air entering the 
building at A is either forced upward through the ventilat- 
ing flue at D or out through any openings which may be in 
the leeward walls of the room. That portion forced past B 
along the roof, across the top of the ventilator, joins with 
the general wind current of that level and tends to drive 
the out-coming air from the flue forward, diminishing the 
pressure of the air downward into the flue, thus making less 
resistance for the air in the room below to be overcome in 
its ascent. The air flowing over the roof of the building in- 
creases the pressure on the leeward side at E, out from 
which air flows on both sides, that flowing toward the build- 



50 



Ventilation. 



ing rising along the sides or entering it at F, as indicated 
by the small arrows. Thus two sources of power are 
brought into operation, compelling air to enter the room at 
A and F and leave it at D, one being the direct wind pres- 
sure exerted at A and F and the other the suctional effect 
developed at C. The flow through the building, resulting 
from wind pressure and wind suction, will be most rapid 






Fig. 23. — Showing improper installation of ventilating flues just above the 
eaves. In such cases whenever the wind is from the opposite direc- 
tion the tendency will be to give a much reduced draft or even reverse 
its direction, causing it to be downward into the stable. 

when these two factors can be made to act in the same direc- 
tion and with the highest efficiency. This will be the case 
when the wind is permitted to reach the building at A and to 
pass over its roof at C, meeting with the least obstructions. 
The table, page 57, indicates that the flow due to direct 
pressure is stronger than that due to suction under like 
wind velocities. It will generally be true, however, that the 
suctional effect of the wind is the stronger of the two for 
the reason that the wind velocity at the top of the ventilat- 
ing flue will nearly always be materially stronger than near 
the ground. The fact of wind velocity increasing with 



Defective Outtake Shelter. 



51 



hight above the ground is expressed in Fig. 22 by the 
length of the arrows, these being aprpoximately propor- 
tional to the wind velocities at such levels. 

It will be clear from what has been said that the top of a 
chimney or a ventilating flue should rise well above the 
ridge of the roof, where the wind has a clear sweep, and not 
end just above the eaves as is the case illustrated in Fig. 23. 

So, too, it must be clear that anything which checks the 
velocity of the wind across the top of a chimney or ventilat- 
ing flue, or which resists the escape of air from them, must 
reduce the power of the wind to produce draft. Such caps, 
therefore, as are seen in Fig, 23 and as is represented on a 
larger scale in Fig. 24, designed to keep out the storm, must 
necessarily materially reduce the draft and should be 
avoided wherever possible unless forced ventilation has been 
adopted and the current is maintained by mechanical 
power. 




Fig. 24.— Shelter for ventilating flue, designed for high efficiency in keep- 
ing out rain but which materially reduces the draft in "natural 
ventilation." 

Many forms of cowls have been devised to prevent down- 
draft in chimneys and ventilating flues, and with a view ta 
utilizing the wind to better advantage in producing draft. 
It will seldom happen, however, that these need be resorted 
to in the ventilation of ordinary farm buildings or rural 
schoolhouses or churches. One of the mistakes most often 
made in installing a ventilation system in barns is illus- 
trated in Fig. 25, where a one-story barn is provided with 



52 Ventilation. 

short ventilating flues which, because they are short, have a 
low efficiency and then this efficiency is still further reduced 
by covering the outlet with closely louvred shelters which 
materially diminish the effect of the wind in aiding venti- 
lation. 



i^ 





iFig. 25. — Low ventilating flues having their efficiency much reduced by 
closely louvred shelters, diminishing the effect of the wind in pro- 
ducing draft. 

A much better construction for the ventilating shaft is 
Tepresented in Fig. 26 where the flues are not only higher 
l)ut the outlet is shielded in such a way as not to materially 
impede the movement of the passing wind or the escape of 
the air from the ventilating flue. 

Any condition or cause which changes the density of the 
air in a dwelling or stable, rendering it lighter than 'ai;i 
equal volume outside, tends also to establish and maintain 
a current of air flowing through it. The effect of both heat 
and the addition of moisture to the air of a room is to ren- 
der it relatively lighter than the air outside and so long as a 
difference in density is maintained there is a difference in 
pressure which tends to compel a continuous flow of air into 
and out of the space. 

When air is warmed or cooled its volume changes 7-- 
for each degree F. rise or fall in temperature. Imagine a 



Good Termination of Outtake Flue. 



53 



room containing 491 cubic feet, one very nearly 8 by 8 by 8 
feet. If the air in this room has its temperature raised one 
degree F. the expansion so caused will force out just one cu- 
bic foot of this air and so, if the temperature is raised 100 
degrees, there will be forced out of such a room 100 cubic 
feet and the air remaining will weigh about 8 pounds less 
than an equal volume outside. This being the case there 
must result a pressure inward tending to force air into the 




Fig. 26. — Ventilating flues rising high above the roof and with outlet 
sheltered so as to permit free wind movement and easy escape of air 
from the flues. 



room, a pressure equal to about .08 pound for each degree 
difference in temperature, and hence 8 pounds where the 
difference is 100° F. Referring now to Fig. 27, which rep- 
resents a room of 491 cubic feet capacity, suppose there is 
an opening of one square foot area in the floor at A and an 
equal similar opening in the ceiling at B. If the air in this 
room is maintained at 70° when the outside air is 30° below 
zero its weight will be 8 pounds less than that of an equal 
volume outside. This being true the pressure into the-i'oom 
at the floor and on sides and ceiling must be 8 pounds 
greater than that exerted outward by the inside air ; and 
since the floor has an area of nearly 

8 X 8 = 64 sq. ft. 



54 



Ventilation. 



the pressure tending to force air into the room at the floor 
opening and out at the ceiling must be one sixty-fourth of 8 




Fig. 27, — Difference in temperature as a motive power in ventilation. 



pounds, or . 125 lb. per square foot. This too is the differ- 
ence in weight between a column of air one square foot in 
section the hight of the room and an equal column outside. 
So long, therefore, as such a difference in temperature is 
maintained air must tend to enter at the floor and flow out 
at the ceiling at the rate which a pressure of . 125 pound 



Difference of Temperature a Motive Power. 55 

per square foot is capable of maintaining, which theoret- 
ically is more than 25,000 cubic feet per hour. 

The magnitude of the temperatue effect in producing 
draft is given by the equation. 

Cu. ft. per hour = 60 X 60 X 8 -. / ^ ~ ^ H 

V 491 

ivhere 

60 X 60 is number of seconds per hour; 

8 is ^ 2o-, and g is the increment of gravitj^ 32.16; 

T is temperature of the air inside; 

t is temperature of the air outside; 

H is height of room, chimney or ventilator: 

^li is the expansion of air for 1° F. 
Suppose a ventilation flue one square foot in section 40 
feet high, and the air in it maintained at a temperature 20° 
above the air outside. In such a case the theoretical flow 
through the flue would be 18,381 cu. ft. per hour.^ 

This is the theoretical rate of flow, no account being taken 
of friction or other forms of resistance. The actual flow 
which would be associated with such a difference in pres- 
sure might be fully 50 per cent less than this. 

The effect of temperature differences in producing draft 
increases with the hight of the chimney, ventilating flue, 
and with that of the room or stable. It is because of the 
greater leakage of warm air from rooms and stables with 
high ceilings that it is more difficult to keep them warm. 
This will be readily seen from a consideration of the prob- 
lem presented in connection with Fig. 27, considering the 
room to have a hight of 16 instead of 8 feet. Such a room 
would contain twice the volume of air and hence, with the 
same increase in temperature, the expansion would cause 
an escape of 16 instead of 8 cubic feet of air. The air of 
the room would then be lighter than an equal volume of 
that outside by the weight of 16 instead of 8 cubic feet, and 
hence there would be double the pressure forcing the air 
to enter and leave the room. Computing the theoretical 

1 60 X 60 X 8 T / — X 40 = 18381 cu. ft. per hour. 
1/491^ 



56 



Ventilation, 



change of air in the two rooms we shall have for the one 
with the 8-foot ceiling 36,760 en. ft. per hour/ and for the 
room with a 16-foot ceiling the rate of air change would 
be 51,889 cu. ft. per hour. 2' If the two rooms under 
consideration were not provided with special openings 
for the' entrance and escape of air, as represented in 
Fig. 27, and the air was required to enter entirely- 
through leaks in the walls, approximately the same rela- 
tive changes of air would take place and it is clear that, 
it is much more economical, both in cost of construction and 
in that of maintaining proper temperature to place the ceil- 
ings of dwellings and stables only so high as is needful to 
secure convenience and sanitary conditions; aiming to se- 
cure the necessary rate of change of air through definite 
provisions in the way of ventilation. It is clearly much 
cheaper to construct a tall ventilating flue for securing the 
necessary increase in the rate of air change, than it is to 
make the walls of rooms and stables higher. 

In the table which follows there are given the theoretical 
rates of flow of air through ventilating flues of different 
hights and under several differences of temperature main- 
tained inside and outside the flues. 

Computed theoretical floio of air through straight ventilating jiues one 
square foot in cross-section, of different lengths and under 8 tempera- 
ture differences. The ohserred floics are likely to he near 50 per cent 
heloiD these values. 



Difference 

in temp. 

T-t. 




Height oe 


VEXTILATIXG FLITE, H. 


• 


20 ft. 


30 ft. 


40 ft. 


50 ft. 


60 ft. 


1° 


5.828 
18.409 
26.064 
31.922 
36.902 
41.211 
45.144 
48,761 


Flow, 

7.138 
22, 572 
31. 775 
39.096 
45.144 
50.472 
55. 291 
59,920 


cubic feet pe] 

8,^42 
26,064 
36. 680 
45.144 
52. 128 
58, 214 
63.843 
68.958 


r hour. 

9,215 
29,114 
41.211 
50.472 
58.214 
65. 159 
71,378 
77,098 


f 10,095 


10° 


31,922 


20° 


45,144 


30° 


55,291 


40° 


63.843 


50° 


f 71,378 


60° 

70° 


78. 192 
84, 457 



1 60 X 60 X 8 



/lOO 
1/ 491 



X 8 = 36760 cu. ft. per hour, 



/lOO 



2 60 X 60 X 8 -, ./ ±^ X 16 = 51889 cu. ft. per hour. 



Capacity of Outtake Flues. 



57 



The relation between wind velocities and the pressures 
due to impact and to suctional effect are given in the next 
table, together with the flow of air computed, using the 
formula on page 55, where the wind pressures in the third 
and sixth columns have their temperature difference equiva- 
lents computed and given in the fourth and seventh col- 
umns, these being used with the formula named. 

Computed theoretical floio of air through a flue one square foot in cross- 
section and 40 feet long, due to the direct impact and suction effect of 
wind at different velocities. 



Velocity of wind. 



Per 
hour, 
miles. 


Per 

sec, 
feet. 


1 


1.47 
2.93 
4.40 
5.87 
7.33 
8.90 
9.87 
11.73 
13.20 


2 


3 

4 

5 

6 


7 


8 


9 


10..' 


14.67 


11 


16.13 


12 


17.60 


13 


19.07 


14 


20.53 


15 


22.00 



Direct impact. 



Suctional effect. 



Press- 
ure. 
Inches 
of water.: degrees. 



Flow 



Eciulva- 

^^r^\^* per hour, 
^-^- ' cu. ft. 



.001 

.0039 

.0087 

.0155 

.0242 

.0.349 

.0475 

.0620 

.0785 

.0969 

.1172 

.1395 

.1638 

.1903 

.2082 



.a 

3.07 

6.90 

12.26 

19.17 

27.59 

37.56 

49.06 

62.09 

76.65 

92.75 

110.38 

129.54 

150.54 

172.62 



7. 
14. 
21, 
28. 
36. 
43. 
50, 
57, 
64, 
72. 
79. 
86, 
93. 

100. 

108, 



201 

402 

603 

804 

005 

205 

406 

607 

808^ 

009 

201 

411 

612 

813 

014 



Press- 
ure. 
Inches 
of water. 



.0005 
.0021 
.0047 
.0083 
.0130 
.0187 
.0254 
.0332 
.0420 
.0518 
.0627 
.0746 
.0875 
.1015 
.1166 



Equiva- 
lent as 

T-t. 
deg^rees. 



Flow 

per hour, 

cu. ft. 



.41 

1.64 

3.69 

6.56 

10.24 

14.75 

20.08 

26.23 

33.19 

40.98 

49.59 

59.01 

69.25 

80.32 

92.20 



5.272 
10. 545 
15,817 
21.089 
26.362 
31.634 
36. 906 
42, 178 
47,451 
52.723 
57,995 
63,268 
68. 540 
73,812 
79. 085 



If the flow of air through a ventilating flue 40 feet high 
and one square foot in cross-section, as given in the two 
tables, is compared it will be seen that differences of temper- 
ature inside and outside the flue ranging from one degree 
to sixty degrees F. are associated with computed air move- 
ments increasing from some 8,000 cubic feet with a differ- 
ence of one degree F. to 63,000 cubic feet per hour when the 
difference in temperature is 60° F. ; while wind velocities 
ranging from one mile to nine miles per hour, acting by 
direct impact, and of two miles to twelve miles per hour 
acting by suction, give approximately equal rates of flow. 
If the actual velocities were one-half these computed 
amounts the slowest rate of movement would a little more 



58 Ventilation. 

than meet the needs of one cow while the most rapid move- 
ment would permit a flue one square foot in cross-section to 
supply nine cows at the rate designated on page 41, 3,542 
cubic feet per hour. Such a rate of movement, too, through 
a flue one-fourth of a square foot in cross-section would, at 
one half the slowest rate, supply air to 2 persons, and, at 
one-half the fastest rate, to 15 persons. 

The wind velocities which are effective in producing draft 
in dwellings and stables probably do not have a yearly 
average in most parts of the United States greater than 
four to six miles per hour. Taking the average flow due to 
impact equal to that computed for the four mile wind, and 
that due to suction equal to the computed value for a six 
mile wind, and supposing further that these effects are fully 
additive, the mean flow due to wind action would be some 
60,000 cubic feet per hour, one-half of which may be lost in 
overcoming unavoidable resistance, thus leaving 30,000 cu- 
bic feet per hour of effective flow, which is sufficient to meet 
the needs of more than eight cows. 

The temperature difference effective in ventilation, not 
including heated chimneys, is perhaps not higher on the 
average than 20° F. for stables nor than 50° for dwellings, 
the first difference being capable of producing a flow of 
36,000, and the second 58,000, cubic feet per hour in a 40 
foot flue one square foot in section. If this motive power 
due to difference in temperature be added to that derived 
from wind action the resulting flow would be some 96,000 
cubic feet of air per hour for stables and 120,000 for dwell- 
ings, having in mind theoretical flows and a ventilating flue 
40 feet high and one square foot in section. Dividing these 
results by two, to allow for loss of power in overcoming re- 
sistance, the remaining motive power should be capable of 
producing a flow of 48,000 cubic feet per hour for stables 
and 60,000 for dwellings. 

In his * * Air Currents and the Laws of Ventilation ' ' Shaw 
cites experiments wherein the observed velocity of flow 
through 3-inch metal flues about 25 feet long varied from 
7,482 feet per hour, when the wind velocity was at the rate 



Observed Air Movement Through Outtdkes. 59 

of 2.5 miles, to 20,064 feet when the velocity of the wind 
was 15 miles per hour. The observed flow associated with 
a wind of 4 miles per hour in these experiments was 8,448 
feet, and with 6 miles, about 10,000 feet per hour. At the 
4-mile rate of flow a square- foot flue would meet the needs 
of only 2i adult cows, and the 6-miles rate, not quite 3 
cows. In these trials all resistance is taken into account, 
the flows being actual, but in ordinary ventilation there 
would be added the temperature effect which might nearly 
double the efficiency. 

In the dairy stable of the Wisconsin Experiment Station, 
represented in Fig. 53, page 112, with a ventilating flue ris- 
ing 60 feet above the floor and with the main shaft 40 in- 
ches in diameter, the observed flow of air during one week 
was as follows: 

1st day 205,377 linear feet 

2nd day 205,800 linear feet 

3rd day .247,852 linear feet 

4th day 242,854 linear feet 

5th day 151,974 linear feet 

6th day 132,822 linear feet 

7th day " 153,720 linear feet 

Here is an observed average velocity of air through the 
main ventilating flue of 7,978 feet per hour. In this stable, 
however, there are but 10 fresh-air intakes, each with an 
area of 3 by 12 inches and each of these is covered with a 
register face which reduces their efficiency to some ex- 
tent so that the aggregate area for fresh air intakes is less 
than 2.5 square feet. The walls and the ceiling of the 
stable are covered with galvanized iron and therefore prac- 
tically air-tight except for leakages about doors and win- 
dows. If all of the air passing through the ventilating flue 
had entered the stable through the fresh-air intakes the 
velocity through them must have exceeded 27,000 feet per 
hour which, with a flue one square foot in cross-section, 
would supply nearly sufficient air for 8 cows. 

In the four stables of H. McK. Twombly, Fig. 26, page 53, 
at his Florham Park farms, New Jersey, in July, when the 
cows were out after milking at night, with a wind move- 
ment outside near the ground less than 50 feet per minute^ 



60 



Ventilation. 



the rate of air movement was found to be as recorded be- 
low: 





Doors and win- 
dows open, 
per hour. 


Doors and win- 
dows closed, 
per hour. 


stable No. 1 


feet. 

11,040 

7,740 
8,340 
8,640 


feet. 

8.620 


Stable No. 2 


7,860 


Stable No. 3 


9.180 


Stable No. 4 


6,960 






Averag"e 


8,940 


8,160 







The ventilating flues in these stables were 30 feet high, of 
galvanized iron ; 4.5, 3.5, 3 and 5 . 5 square feet respectively 
in cross-section, there being two for each stable. It will be 
observed that in this case the velocity of discharge through 
the ventilating flues averaged somewhat less with the doors 
and windows closed although the cross-section of the fresh- 
air intakes aggregated 6, 4.3, 4.6 and 6 square feet for the 
several stables, rather more than the cross-section of the 
ventilating flues. These intake flues, however, were covered 
outside and in with register faces which reduced their 
effective cross-section probably below that of the ventilators 
themselves. Under these conditions the available motive 
power for ventilation was probably near its minimum for 
the air near the earth's surface outside was alipost calm 
and the cattle were out of the stable so that the only avail- 
able heat for ventilation was the little that may have been 
retained by the walls to be given out during the night. 
Notwithstanding the low available motive power the wind 
movement through the ventilation flues was sufficiently 
rapid so that a current a square foot in cross-section was 
2 . 5 times that needed for one cow. 

The influence of moisture as a motive power in ventila- 
tion is measured by the effect the amount transpired or 
otherwise added to the air has in making that within the 
space to be ventilated lighter per cubic foot than that out- 
side. Take the case of air outside at 30^^ and Aveighing 
.08107 pound per cubic foot entering a stable, becoming 
charged with moisture to the extent of saturation at 45^ 



Moisture as a Motive Foiver. 61 

and having its temperature raised so as to remain at 50° 
when in the ventilating flue. Air so changed will be re- 
duced to a weight of . 07747 pound per cubic foot, thus giv- 
ing rise to a motive power in a ventilating flue 40 feet high 
equal to .027 inch of water/ and this pressure reduced 
to its equivalent value in temperature becomes 21.8° F.^ 
This value, 21.814° F., represents the combined effect of 
change in temperature and 'change in moisture content of 
the air. As the change in temperature between 30° and 
50° is 20° the moisture effect must have a temperature 
equivalent of 1.8° F. This temperature equivalent, acting 
as a motive power, or aeromotive force, as it has been 
called, is capable of producing a theoretical flow in a 40 
foot flue of 11,073 cu. ft. per hour.^ The motive power 
derived from moisture added to the air of a venti- 
lated space is always operative in assisting ventilation 
and its magnitude is the greater the more completely 
the air is saturated, the higher is its temperature and the 
longer the ventilating flue. In order, therefore, to most 
fully utilize the effect of moisture as a motive power in ven- 
tilation it is necessary to construct warm stables and to so 
place the ventilator that its walls may remain as warm as 
practicable, thus avoiding condensation of moisture before 
leaving the flue. 

It not infrequently occurs that the motive force due to 
wind pressure and wind suction is very small or even zero. 
We have found, for example, that at Madison, at the labor- 
atory very near the shore of Lake Mendota, where the wind 
movement was measured at an elevation of 120 feet above 
the lake and 82 feet above the ground, there were 16 days 



1 (.081074 — .077472) X 40 .^^^ . , 

^ — — -^ = ,0277 men water pressure 

5.2017 

.0277 X 491 X 5.2017 _ 

^-^- — 4oor:o8io74 — - ^^-^^^ ^• 



■^ 60 X 60 X 8 1 /^•^44 w ^Q = 11073 cubic feet per hour. 
1/ 491 -^ 



62 Ventilation, 

m January when during the night, the time when stables 
are most tightly closed, the wind velocity did not average 
five miles per hour during any 10 consecutive hours be- 
tween 7 p. m. and 7. a. m. On 10 of these nights the 
recorded wind movement during more than an hour was 
either zero or less than one mile. At such times as these 
dependence must be placed upon the motive power derived 
from rise in temperature and from an increase in the moist- 
ure content of the air after it enters the stable. It is im- 
portant therefore to know what the minimum motive power 
from temperature and from moisture changes is likely to be 
as this knowledge is fundamental in determining the proper 
dimensions for the ventilating system. 

As dairy stables will seldom need to be tightly closed 
when the outside temperature is above 30° F. and as at this 
temperature that of the stable is likely to be as high as 50° 
F. it may be assumed that the minimum motive power avail- 
able for the ventilation of such stables is likely ta be not 
less than that given when the outside air enters, saturated 
with moisture, at 30° and when the air leaves the stable at 
a temperature of 50° and containing only 3.3 per cent of 
air once breathed. Under these conditions the entering air 
would weigh .0809 pounds per cubic foot and before enter- 
ing the ventilating shaft would be reduced by changes in 
temperature and composition to .0777 pound per cubic 
foot, thus giving rise to a motive power in a ventilating 
flue 40 feet high equal to .02461 inch water pressure, 
whose equivalent, expressed in difference of temperature, is 
19.422° F. This difference in temperature is capable of 
giving a flow of 36,227 cubic feet per hour through a ven- 
tilating shaft one square foot in cross-section and 40 feet 
high. This value is the theoretical flow. Taking the effect- 
ive flow equal to one-half this amount we shall have an 
hourly supply equal to 18,113 cubic feet or 301 cubic feet 
per minute. A velocity of 295 feet per minute in a flue 2 
by 2 feet in cross-section will supply 20 cows at the rate of 
3,542 cubic feet per hour and per head, and this is the 
amount needed, as previously stated, that the air of the 



Proper Dimensions of Outtake Flues. 63 

stable shall remain 96.7 per cent pure or shall contain at no 
time more than 3.3 per cent of air once breathed, the stand- 
ard we have assumed as possibly permissible for dairy 
cows. 

In the case of barns for sheep, piggeries and especially 
poultry houses, where lower differences of temperature are 
quite certain to occur, the motive power must necessarily 
be less when the wind movement is small. Besides, in these 
cases, it will seldom be practicable to construct as long ven- 
tilating flues hence relatively larger shafts must be in- 
stalled or other equivalent means adopted for securing the 
desired change of air. 

To make clear this fact let us assume a poultry house for 
the accommodation of 50 hens each needing 35 cubic fee\ 
of air per hour, as stated on page 41. The vetitilating flus 
must therefore provide for 50 times 35 cubic feet, or 1,750 
per hour. Let it be assumed that the ventilator has a 
length of 16 feet; that a temperature difference of only 4P 
is maintained in it when the outside temperature is 30° F. ; 
and that the rate of air movement is to be such as to main- 
tain a purity of 96.7 per cent with a moisture saturation 
at 34° of 90 per cent. With the outside air saturated at 
30° and with the composition, page 13, its weight will be 
.0809 pound per cubic foot, and that in the ventilating 
shaft, at 34°, 90 per cent saturated and containing 3.3 
per cent of air once breathed, having the composition of 
that stated on page 14, would weigh .08024 pound. This 
gives a difference of pressure between the air in the 16 
foot shaft and that of an equal column outside of .00066 
pound per square foot. Reducing this to its temperature 
difference equivalent it becomes ..2504° F. Using this 
value to compute the theoretical flow the result becomes 
2601.3 feet per hour, which, at half this value, leaves an 
effective flow equal to 1300.6 feet. But the 50 hens re- 
quire 1,750 cubic feet of air per hour. The size of the ven- 
tilating flue must therefore be 
1750 



1300.6" 



: 1.346 square feet. 



64 Ventilation. 

This area is given by a rectangular flue 14 inches on a 
side and by a circular one 15.7 inches in diameter. 

MAINTENANCE OF TEMPERATURE WITH AMPLE VENTILATION. 

It may appear that the movement of such large volumes 
of air through stables and dwellings as have been consid- 
ered needful in ventilation is incompatible with comfort 
and economy as regards warmth. Let us see what are the 
facts : In the first place we .need to understand that nearly 
all the food assimilated or utilized in the body, like fuel 
burned in the stove, gives rise to a certain amount of heat 
so that every animal and person is in a sense a heat gen- 
erating mechanism. It is estimated that a cow produces 
and gives oif from her body daily, as a result of changes 
taking place in the food she eats and air she breathes, an 
amount of heat equal to 76,133 British thermal units, heat 
sufficient to raise from 32° F. to boiling 423^ pounds of 
water and it is enough to raise the temperature of 
79,603^ cubic feet of dry air from 0° F. to 50° F. 
Thus it appears that the heat generated by one cow dur- 
ing 24 hours is sufficient to warm approximately 79,600 cu- 
bic feet of air through 50 degrees F. or at the rate of 3,316 
cubic feet per hour. This amount is only 226 cubic feet of 
air less than has been taken as possibly sufficient to meet 
the needs in dairy stables. It should be understood that 
during the winter in the United States only occasionally is 
the outside air at a temperature as low as 0° F. Indeed 
the mean temperature for "Wisconsin for January is nearly 
15° and a rise of 50 degrees above this would give a stable 
temperature of 65°. Taking Doctor Jordan's estimate of 
the heat given off by a cow daily equal to 76,133 British 
units, and 3,542 cubic feet of air per hour as the amount 
needful for each cow, and supposing that the whole of the 



= 422.96 pounds of water, 
180 

2 76133 



50 X .237 X .08071 



= 79603 cubic feet. 



Temperature Maintenance with Ventilation. 65 

heat so generated is lost through the air passing into and 
out of the stable, this heat is capable of warming the unit 
volume of air through 47.55 degrees F. and, on this as a 
basis, the following table is computed, showing approxi- 
mately the temperature of stable air when it enters at dif- 
ferent temperatures at the rate of 3,542 cubic feet per hour 
and per cow. 

Approximate temperature of stable- air resulting from animal heat, when 
entering at different temperatures at the rate of 3542 cubic feet per 
hour and per cow. 



Temperature of 


Temperature of 


outside air. 


inside air. 


— 32°F. 


15.55°F. 


-10 


37.55 





47.55 


10 


57.55 


15 


62.55 


20 


67.55 


25 


72.55 


30 


75.55 



Of course some heat is lost in other ways than through 
the air entering and leaving the stable so that lower tem- 
peratures than those in the table must be expected under 
the conditions stated but, as the average winter temperature 
in the United States is materially above 10° it is clear that 
good ventilation for dairy stables is possible and yet permit 
reasonable temperatures to be maintained. As a specific 
example of temperatures actually maintained the table 
which follows is cited, wherein are given the mean daily 
temperature of the dairy stable at the Wisconsin Agricul- 
tural Experiment Station, during two weeks, together with 
the outside temperature, the total air movement through 
the stable and the cubic feet of air per cow and per hour, 
as observed by E. L. Jordan in a thesis study relating to 
the influence of temperature on milk production. 



66 



Ventilation. 



Mean daily temperatures and air movement through a dairy stable 

containing 31 cows. 





Average Temperature. 


Flow of air. 


Date. 


Stable. 


Outside. 


Total per 
hour. 


Per cow per 
hour. 


January 13 


56° F. 
49 
50 
50 

47 
47 
54 
51 
50 
48 
47 
43 
44 
44 


13'' F. 
13 

20 

14 

13 

18 

28 

27 

25 

21 
— 2 
—18 
—16 
—11 


Cu. ft. 

83.621 
86.965 
80.591 
83.522 
85. 596 
89.768 
88, 435 
81.578 
105. 107 
.92.317 
83.479 
77.632 
81,882 
100.964 


Cu. ft. 
2 697 


Janu ary 14 


2.805 


January 15 


2.600 


January 16 


2.694 


January 17 


2,761 


January 18 


2.896 


January 19 


2.853 


January 20 


2.632 


January 21 


3. .391 


January 22 


2.978 


January 23 


2.693 


January 24 


2.508 


January 25 


2.641 


January 26 


3. 257 







This table shows that with the outside temperature rang- 
ing from 28° to -18°, a range of 46 degrees, the stable tem- 
perature varied between 43° and 56°, a range of but 13 de- 
grees, the temperature maintained entirely by the heat of 
the animals and this with a measured flow through the ven- 
tilating shaft at no time less than 2,500 cubic feet per cow 
per hour. In addition to this flow of air through the stable 
by way of the ventilator there was undoubtedly a material 
leakage through the windows and other openings which 
would carry the air supply well toward, if not above, 3,542 
cubic feet, the standard assumed as possibly adequate. 

The amount of heat required for warming the needed 
amount of air for good ventilation is not as great as might 
be expected from its large volume for the reason that it is 
very light and because its specific heat is very low, only 
.237 as compared with 1 for water, pound for pound. 
That is, it takes as much heat to raise a pound of water one 
degree as it does to raise 52 cubic feet of air through the 
same range of temperature. With hard coal at $10.00 per 
ton and of the usual fuel value ; with the outside air at zero, 
to be raised to 72° inside, and supplying 10 persons during 
24 hours at the rate of 537 cubic feet each per hour, only 



Little Extra Heat Needed with Good Ventilation. 67 

11.26 pounds of coal would be required to furnish the 
needed heat, making the fuel cost but 5.63 cents per day 
for thus warming the necessary amount of air for 10 people. 
This statement must be understood as meaning that the ex- 
tra amount of heat in house warming required for proper 
ventilation is but very little above that required where only 
poor ventilation exists. Stated in another way, to main- 
tain the proper temperature in the house when the tempera- 
ture outside is zero, without any ventilation whatever, re- 
quires a certain amount of fuel, this varying with the type 
of construction. To warm the necessary amount of air re- 
quired for good ventilation during 24 hours would in real- 
ity cost less than 5 . 63 cents extra for 10 persons where coal 
is $10.00 per ton, because a part of this heat would also be 
available for maintaining the proper temperature. There 
is therefore little ground for providing insufficient ventila- 
tion because of extra expense needed for fuel. But in or- 
der that the maximum air movement through stables may 
be secured without the aid of artificial heat or mechanical 
appliances and that good ventilation for dwellings, schools 
and offices may be had without unnecessary cost it is im- 
portant that, so far as possible, the exhaust should be from 
the coldest part of the room which will be usually the floor 
level. 

There is a general impression that because respired air, 
before leaving the lungs at the temperature of 93° to 97° 
F. is lighter than pure air at room and stable temperatures 
it must rise at once to the ceiling and that for this reason 
ventilating flues should exhaust from that level rather 
than from the floor. The facts are that respired air so soon 
as it leaves the lungs and becomes cooled below 81° is 
heavier than pure air at the same temperature because of 
its increased content of carbon dioxide, the moisture it is 
capable of holding below 81° not being sufficient to com- 
pensate for the increased weight due to the carbon dioxide 
added. The fact will be made clear by an inspection of 
the next table. 



68 



Ventilation. 



Weight of a cubic foot of pure air and of air once respired iy man at 

different temperatures. 



Temperature. 


Pure air 
composition. 
O 20.61% 
CO 2 .03% 

HgO .55% 

N 78.81 


Respired air 

composition. 

O 15.725 

COg 4.350 

HgO 2.000 

N 77.925 


70° 


.074316 


.075223 


64 


Saturated 


60 


.075961 
.077605 
.079249 
.080894 
Saturated 


.076884 


50 


.078544 


40 


.080205 


30 


.081865 


29.8 









Here it is seen that air changed in composition by being 
respired and cooled to temperatures between 70° and 30° 

is heavier than pure air at 
the same temperature. As 
soon as respired air cools be- 
low the temperature at which 
it becomes saturated by its 
contained moisture a portion 
of this must be condensed, 
leaving it heavier because of 
this loss of moisture. Thus, 
in the colume of respired air, 
it is seen that it becomes sat- 
urated at 64° and' when it is 
cooled to 50°, instead of 
really having the weight 
there stated, on the basis that 
it could contain 2 volume per 
cent of moisture at that tem- 
perature, its actual weight 
when saturated is .078765 
pound per cubic foot, which 

Fig. 28.— Inverted jar being is 1.49 per cent heavier than 
filled with respired air. ^^^^ ^.^ ^^ ^^^ ^^^^ temper- 

ature. 




Density of Respired Air. 



69' 



That respired air, when surrounded by pure air, either 
rises very slowly or tends actually to fall may be clearly 
demonstrated. Let the Mason jar earlier used be inverted,. 
Fig. 28, while air from the lungs is made to displace that 
which it contains. With the candle already lighted let the 
jar be at once lowered over 
it, Fig. 29. The flame is ex- 
tinguished as it was in an 
earlier experiment when the 
candle' was lowered into the 
jar filled with respired air. 
But if the trials are now re- 
peated with the jar both in- 
verted and placed with 
mouth up it will be found, 





Pig-. 30. — Respired air soon 
drops from the inverted 
jar and the flame is not 
extinguished. 



Fig. 29. — Respired air in in- 
verted jar extinguishes flame 
if lowered over it quickly. 



Fig. 30, that with the in- 
verted jar materially less time 
is required ' for the respired 
air to become so changed as 
to permit the candle to burn 
in it than is the case when 
the jar stands mouth up. This 
could not be the case did not 
the rspired air, cooled by the 
walls of the jar, become 
quickly heavier than that 
outside. 



70 



Ventilation. 



These experiments and statements are in apparent con- 
tradiction to the results of some analyses of stable air, as 
in the case in the dairy stable at the New York Agricul- 
tural Experiment Station, represented in Pig. 31, where 
Dr. Jordan found, as an average of analyses made on two 
different dates, results given in the following table : 

Composition and temperature of air at the floor and ceiling of the dairy 
stable at the New York Agricultural Experiment Station. 





Ventilator 
working. 


Ventilator 
closed. 


Temperatvire of air. 

At ceiling' 


56.3°F. 
50.0 


64.4°F. 


At floor 


56.3 






Difference 


6.3 

.4815 
.7198 


8.1 


Composition, volume per cent. 

HgO at ceiling" 


.525 


HgO at floor 


.5465 






Difference 


.2383 

.5335 
.351 


.0215 


CO ^ at ceiling 


1.4 


CO, at floor , .... 


1.0335 






Difference 


.1825 


.3665 







These analyses of Doctor Jordan and those of similar im- 
port niade by other analysts appear to the writer not 
in necessary contradiction with the statements made, and 
that they should not be thought to indicate that it would 
be better for ventiltors to exhaust from the ceiling rather 
than from the floor level. In the case of the New York 
stable it appears probable that the circulation of the' in- 
terior air, as indicated by the arrows in Fig. 31, tends to 
•carry the respired air directly to the ceiling mechanically,- 
notwithstanding its greater weight, thus giving the ob- 
sei-ved distribution of products. It should be stated, to 
make the situation more clear, that the samples of air ana- 
lysed were taken at the center of the stable between the 
two mangers and where there must necessarily be a ma- 
terial mechanical effect tending to maintain an upward 
•current. 



Principles of Ventilation Construction. 71 

But whatever may be the truth relative to the distribu- 
tion of products of respiration in dwellings and stables 
this we think, should hold in all good practice : Maintain 
a sufficient air movement through dwellings and stables to 
insure the entire air content in every case being sufficiently 
pure for thoroughly healthful conditions. It is hardly pos- 
sible to make the air movement for ventilation too large so 
long as the temperatures are right and there can be no 
doubt that the largest air movement with proper tempera- 
tures is possible only when ventilating flues exhaust from 
near the floor level. It is important to remember, too/ in 
this connection, that whether waking or asleep, whether 
standing, sitting or lying, the supply of air breathed must 
be drawn from near the floor level and that removing all 
air from this level compels the return of an equal volume 
to it. 

To fully utilize the heat of dwellings and stables in 
economic warming and in securing adequate ventilation it 
is imperative that certain principles of construction arid of 
admitting and of removing air should be adopted. Speak- 
ing here from the standpoint of stables, without artificial 
heat or forced ventilation, each animal must be regarded as 
a heater which is warming the air of the compartment in 
three ways: (1) by direct contact of the air with the 
body; (2) by rapidly breathing large volumes of it and 
raising its temperature at once to between 93° and 97° F. ; 
(3) and by direct radiation of heat to_ walls, ceiling and 
floor which in turn warm the air by contact. Because the 
warmed air is thus rendered lighter it is forced at once to 
the ceiling where it tends to collect, while the coldest air, 
settling toward the floor, gives rise to an internal system of 
circulation represented by the arrows in Fig. 31. It will be 
seen from this illustration that the circulation of the stable 
air is maintained by the continuous action of three motive 
forces; (1) the waste heat of the occupants which becomes 
effective through its expansion of the air; (2) the mechan- 
ical or bellows-like action of the chests of the cattle and (3) 
the loss of heat by conduction through the outer walls. 



72 



Ventilation. 



Referring to the figure the arrows show that from the bodies 
-of the cows convection currents rise directly toward the 



^'-- 




^ > ^u^ / 



:iv&^::?.>M^¥'>:' 






"'^^''iL' 



1 ^ 1 


^ 1 


1 


in 


1 ^ 1 


^ 

4 


^ E=t 


1 ^ 1 


m 


m 


1 ^ 1 


1 ^ i 


"^ 


% 


m 


Dl 


1 ^ 1 


1 '^ 


3 S 


■ 1 - 


^ 


1 ^ 



Fig. 31. — Section of cattle barn at New York Agricultural B'xperiment 
Station. I, illustrating convectional system of air currents main- 
tained by the animals and the cooling of the outer walls. II, side 
elevation of stable viewed from inside, showing AA, floor entrance to 
ventilating flues; BB, ceiling openings to ventilating flues; GGG, 
ceiling openings to fresh air ducts; WWWWWW, windows, and DD, 
doors^ III, side elevation of stable viewed from outside showing 
GGG, openings to fresh air duots. 

ceiling; that with the cows facing each other the bellows- 
like action of each row forces the air currents so formed to 
meet in the center and the air must rise and then flow out- 
ward along the ceiling in both directions, finally descend- 
ing along the outer walls, at the same time mixing with the 
incoming fresh air entering at the several intakes GGG 
shown in the side elevations II and III. During cold 
weather and especially at the windows, unless they are 
double, and all along the walls if not of wood or hollow 
masonry, so as to be poor conductors of heat, the air will 
be cooled, thus rendering it heavier, causing descending 
currents which must flow along the floor, maintaining a 
more or less strongly marked system of air circulation 
within the stable, which tends continuously to mix the re- 
spired air with that entering from without. 



Principles of Ventilation Construction. 73 

From this tendency to the formation of a continuous cir- 
culation of air within the room to be ventilated it is clear 
that it must be extremely important that both ceiling and 
walls should be air-tight and warm in construction. With 
ceiling and walls tight and poor conductors of heat and 
with no opportunity for air to enter except where special 
provision is made, near the ceiling at GGG inside, II, Fig. 
31, or for it to escape except at the' floor level, only the 
coldest air is permitted to leave the stable, while at the 
same time the fresh air must be mingled with the warmest 
air of the stable, thus having its temperature raised before 
reaching the animals. Where such conditions of construc- 
tion are secured the whole ceiling and upper walls become 
a continuous radiator of heat, sending back to the animals 
and to the floor, where it is most needed, the heat which 
has escaped from them. By admitting the fresh air from 
low do\^Ti outside and at the ceiling inside, as represented 
in Fig. 32, this air entering from all sides as shown by the 
large arrows in Fig. 33, the cold incoming air is thus widely 
and generally mixed with the warmest air of the stable, 
thus having its temperature raised before being brought to 
the animals ; while with the ventilating flues opening at A, 
Figs. 31 and 32, near the floor level, this arrangement not 
only compels the coldest air to be removed but it forces a 
return of the warmest air in the stable, mixed with the 
fresh air from outside, and thus partly warmed, to the floor 
level where it is needed both for warmth and for respira- 
tion. 

So, too, in the ventilation of dwellings, offices and' school- 
houses, as represented in Figs. 44 and 48, by admitting 
the fresh supply of air at the ceiling, where the highest 
temperature exists, not only is the heat being lost by up- 
drafts through leaks utilized to warm the incoming air, 
but all drafts are avoided near the floor level, thus making 
it possible to have maintained the maximum air movement 
through the rooms without danger or discomfort. 



74 



Ventilation. 



Eeferring further to the method of admitting fresh air 
to stables, illustrated in Fig. 31 and 32, it should be un- 
derstood that the position of the outside openings for the 
entrance of air to the fresh air ducts, placed at some dis- 
tance below that admitting the air to the stable, is funda- 
mentally important for the reason that only in this way 
can the escape of the warmest air of the stable through 




'■if^T^Tf 



Fig. 32. — Section of dairy stable showing tlie action of the wind at DD, 
forcing air into the stable by direct pressure at BB and out of it by 
suction at the top of the ventilating shaft AA, At C is a ceiling 
register in the ventilating shaft to be opened only when the stable is 
too warm or when the draft is too feeble. 



such openings on the leeward side be prevented. Without 
some such provision as this the case would be like lowering 
the windows at the top on opposite sides of stable or room, 
which always results in fresh air entering on the windward 
side and warm air escaping on the other. With the ar- 
rangement adopted, as shown in the illustrations, only a 
strong wind pressure can result in forcing the warm air to 
descend and escape through intakes on the leeward side. 



Principles of Ventilation Construction. 



75 



The ventilation of offices which is so often attempted by 
raising a window at the bottom and inserting under it a 
screen carrying a pair of short Tobin tubes, like up-turned 
pipe elbows, while better than no attempt, can seldom give 
adequate ventilation where steam or hot water is used for 
warming for the reason that here provision only is made 
for air to enter and this can take place no faster than 




Fig. 33. — Floor plan of dairy stable, Fig. 32, showing fresh air intakes 
on all sides at the large arrows crossing the walls; two ventilating 
flues are AA and the air approaching them along the floor level indi- 
cated by the small arrows. 



opportunity for escape exists. The opening of the door 
into a hallway or of the transom above it usually has only 
the effect of making the box to be ventilated larger; and 
the result usually is, with such makeshifts, that, on windy 
days during cold weather, such window openings are 
closed to save heat and during still weather there is little 
motive power to force an air movement if they are opened 
and hence much of the time very inadequate ventilation 
must obtain. 



PEACTICE OF VENTILATION. 



In coming to the practice of ventilation in cold -climates 
the problem is reduced to its lowest terms when it is stated 
that the desired results can be ideally secured only when 
the construction of the building to be ventilated is such 
that no air can enter or leave it except at appointed places, 
and when all heat is lost through the outgoing air and 
none, or as little as possible, through the walls. While it 
is not practicable to construct enclosures whose walls are 
either air-tight or perfect non-conductors of heat it is 
;nevertheless of the highest importance, as leading to correct 
practice, that right ideals be held and that they effectively 
direct construction. When nearly all air enters and leaves 
the space to be ventilated at the appointed places and when 
most of the heat is borne away during cold weather by the 
air leaving the room or stable there is secured the largest 
practicable rate of change and the most thorough ventila- 
tion, which is the object sought. Life under these condi- 
tions may live to its fullest capacity, rather than survive 
by the narrowest margin. 

BEST ROOM AND STABLE TEMPERATURE. 

The fires of life, kept alight through all the organs of the 
body by the incessant fanning of the lungs and the tireless 
pumping of the heart, can only be maintained between very 
narrow ranges of temperature. With ourselves and with 
all our domestic animals the temperature within the body 
lies close to 100° F. If the general active tissue tempera- 
lure falls but a few degrees below this life activities must 



Best Boom and Stable Temperature. 77 

cease; within the healthful but narrow range chemical 
changes go forward along normal lines and at the normal 
rate ; at but a few degrees above this temperature reactions 
occur which seriously interfere with body functions, mak- 
ing them abnormal or causing them tO cease. 

Since most of the activities within the normal body re- 
sult in the generation of more or less heat, and since the in- 
ternal temperatures must be kept near 100° F., it is clear 
that surrounding temperatures must be at some lower de- 
gree than that of the body in order that a rate of loss of 
heat equal to that of production may take place. In our 
own case we become uncomfortable when the surrounding 
temperature rises much above 68° to 70° and the same is 
true of our domestic animals. Stables and dwellings then, 
as a rule, should have a temperature lower rather than 
higher than 70°, but how much lower than this is best must 
depend upon various conditions. Persons engaged in 
bodily exercise, and animals being heavily fed, like fatten- 
ing swine, steers or sheep, are likely to do better in some- 
what cooler quarters, (1) because the greater activity as- 
sociated with increased assimilation must develop more heat 
and this must be removed at a more rapid rate, and, (2) 
because the aim in feeding such animals is to induce them 
to eat as much food as can be economically converted into 
the products sought, too warm quarters tending to make 
the need and desire for food less. 

It has been found that when fasting and at rest, under a 
temperature of 90°, a man consumed some 1,465 cubic inches 
of oxygen per hour, but under the same conditions except 
that the surrounding temperature was 59°, 13 per cent 
more oxygen was consumed and a like' increased volume of 
carbon dioxide thrown off, thus showing that more food 
must be eaten to compensate for the increased waste. But 
in eating more to maintain animal heat under lower tem- 
perature surroundings it is probable that more than enough 
to do this may be taken and hence that an increase in the 
formation of useful products will likewise result. When 
animals are simply on a maintenance ration and the aim is 



78 Ventilation. 

to carry them with the least amount of food their quarters 
should then be as warm as the demands of health will per- 
mit. It seems likely that the best temperature surround- 
ings for animals being fed high will be found to lie. between 
45° and 50°, while with animals on- a maintenance ration 
these will be found to do better and to be maintained at a 
lower cost under temperatures between 55° and 65°. ^Mth 
dairy cows, having large udders only scantily clothed with 
hair, and through which so much blood must flow, it may 
be expected that a temperature perhaps as high as 50° to 
60° will be found best, even with high feeding, although 
the few studies known to the writer, which have been made 
to determine this matter, have resulted in inconclusive 
data. 

Because full comfort and complete satisfaction; ample 
and appropriate food and drink properly supplied; and 
sufficient unimpoverished and unpolluted air all of the 
time are the indispensable requirements for the highest ani- 
mal production, and because we have never known an ani- 
mal, however well fed, to voluntarily take to the open field 
in cold weather for rest, we are not yet convinced that a 
conveniently arranged and sufficiently warm shelter ade- 
quately ventilated is not indispensable to the highest results 
from winter feeding and winter maintenance. 

LIGHT FOR DWELLINGS AND STABLES. 

In the construction of every dwelling much care should 
be taken to secure an ample amount of light, in the kitchen, 
in the dining room and above all in the main living rooms. 
An abundance of light is needed not only to facilitate 
work but to make the best of intentions more certain in at- 
taining results. Besides, it requires an effort to be gloomy 
and feel ugly in the face of a hearty laugh and a bright 
sunny, cheerful room has much the same effect upon those 
who occupy it. Many disease germs are enfeebled by di- 
rect sunshine or are destroyed by it. Who has not ob- 
served the cat deliberately seek out the sunny spot on the 



Light for Dwellings and Stahles. 79 

carpet for the good feeling that comes with it and lasts 
after it. A sunny window is equally needed and enjoyed 
by the members of the family whose duties confine them 
so exclusively to the house. 

The number, size and exposure of windows best suited to 
the requirements of dwellings and stables is not well 
established either in philosophy or in practice. It should 
go mthout saying, however, that sufficient window space 
must be provided to admit ample light for doing all 
necessary work with dispatch and efficiency and with- 
out an undue strain upon the eyes. How far beyond 
supplying such an amount of light it is best to go 
there is yet much room for difference of opinion, owing 
to the present state of knowledge, as to the efficiency of 
light of different intensities, as to the best manner of ad- 
mitting light to dwellings and as to its importance in dwell- 
ings and stables as an agent in sanitation. So much is being 
urged upon the public at the present time, especially in the 
matter of lighting dairy stables, as a necessary measure of 
sanitation that it becomes a matter of practical moment to 
have the problem clearly and correctly stated, and the more 
so because efforts to secure unsual lighting are very likely 
to lead to deficient ventilation in dwellings and stables in all 
cold climates. 

It has ever been and it must always remain true that the 
life resultants of every type are necessarily attained 
through compromises. Nature has never been an extremist 
along any line and all of her biologic assets have accrued 
through admitting in partial potency the multitude of fac- 
tors always operative in securing the result, whether that 
be maa, stamped with the highest attainments, or the dead- 
liest microbe pitted against him. And so we are here con- 
fronted with the problem how much of light is most whole- 
some in the dwelling, and how much light may be admitted 
without unduly curtailing other essential requirements. 

In the effort to put into practice the deductions of re- 
search and the recommendations of zealous but not always 
sufficiently informed teachers of stable sanitation many ser- 



80 



Ventilation. 



ious mistakes in construction are being made, one of which 
is illustrated in Fig. 34. This stable is far from the best 
type for use in cold climates. Thus constructed, the short, 
low closely-capped ventilators tend in themselves to provide 
but a small air movement. Then with the row of hiq-h deck 




Fig. 34.— Showing faulty arrangement of windows for stables in cold 
climates, the effect being to render them cold and damp, 

windows there is provided an elevated ceiling space into 
which the warmest air of the stable immediately rises, car- 
rying with it the heat of the stable beyond where it can be 
utilized in warming the incoming fresh air, and where, be- 
cause of great hight and unavoidable leaks, much of this 
warmest air must escape through the roof, tending further- 
more to even carry fresh air direct from the intakes along 
the ceiling and out through the ridge, thus diminishing the 
lower ventilation. Such a stable, unless artificially heated, 
must either be very cold or have a small air movement 
through it. In either case the air must be damp and for 
this reason unsanitary. The side windows in this stable are 
excellent, both in dimensions and exposure, but, in our 
judgment six or seven, instead of ten, on a side, would have 
been ample. 

If it shall be proven imperative to admit more direct and 
sky light into stables for the purpose of disinfection 
then some type of construction embodying the principle 



Lighting of Stables, 



81 



represented in Fig. 35 must be adopted. In a type of con- 
struction like this, with double windows arranged along the 
slope of the roof, and with similar windows in the side both 
direct sunshine and reflected light from the sky may be ad- 
mitted to the stable from all zones to the greatest practi- 
cable extent and at the same time utilize the animal heat 
in keeping the stable warm, thus permitting a maximum 
flow of air through the stable without unduly lowering its 
temperature or rendering.it damp. 




p^ 



Fig. 35.— Cross-section of a concrete one-story dairy stable de-igaed to 
admit tlie maximum amount of direct sunshine and of diffused liglit from 
the whole sky, leaving it at the same time warm in construction so as to 
permit the maximum air movement thus combining sunlight and desicca- 
tion to the greatest practicable extent as disinfecting agents. 

It does not appear likely, however, that such extremes 
of illumination for either dwellings or for stables will be 
found materially better than moderate window space con- 
fined to the walls. It will not be maintained that, even 
out of doors where direct sunshine is at a maximum both in 
intensity and in duration and where the full hemisphere of 
reflected light from the sky is added, bringing illumination 
from every side, all disease germs which may there be 
present are destroyed by the light. Faced by this general 
truth relative to light as a destroyer of disease germs it be- 
comes clear that even glass houses and stables cannot be ex- 
pected to eradicate germ diseases. In dwellings and stables, 
far more than out of doors, shadows cast by litter and fix- 
tures must effectually baffle all efforts to secure anything 
more than partial disinfection through the action of light 
whether coniing direct from the sun or reflected from the 



82 Ventilation. 

sky. The greatest safeguard against germ and all other 
diseases is found in a well nourished and well eared fot 
body and as more than the half of such indispensable nour- 
ishment must be pure air, lighting beyond a fair amount 
cannot be permitted to seriously interfere with the air sup- 
ply of stables or dwellings. 

Dr. Weinzirl, of Washington University, whose has 
made recent critical studies along the line of light as a 
destroyer of disease germs and particularly those of tuber- 
culosis, wrote, under date of Feb. 17, 1908, as follows: 

**In reply to your question as to the value of sunlight in 
stable disinfection and the feasibility of this method I will 
say that in my opinion sunlight is of little value and prac- 
tically of no value under prevailing conditions, nor do I 
believe that it can be made valuable by merely increasing 
the amount of diffused light through side windows. I ex- 
posed tubercle cultures on the window sill on north window 
for a week and yet about one-half of them grew. As to the 
other half I am inclined to think that desiccation, and per- 
haps other factors, entered to kill the culture. At any rate 
non-spore bearing bacteria are more readily killed by dry- 
ing than is generally believed. A day or two will suffice to 
kill many of them. ' ' 

In another letter Dr. Weinzirl qualifies the views as 
above expressed, writing under date of Oct. 19, after the 
other was in type. He says: 

"I have made a good beginning on the problem of im- 
portance of diffuse light and as a result of this work I 
have to revise my views quite materially. 

The shortest time in which diffuse light in a room killed 
the bacillus of tuberculosis was less than a day and the long- 
est time was less than a week; generally, three or four days 
of exposure killed the organism. 

Some pus-producing bacteria required a week's time to 
kill them, while some intestinal bacteria were killed in a 
few hours. It was also found that bacteria are killed more 
quickly in a moist air than in a dry one, contrary to general 
belief. 



Sanitary Effect of Light. 83 

The diffuse light as found in our dwellings is, therefore, 
a hygienic factor of great importance, and where direct 
sunlight is not available, it should be carefully provided 
for.'' 

It may be added as supplementary to Dr. Weinzirl's let- 
ter just quoted that he also made at the same time control 
exposures in the dark which showed, for the six groups of 
trials made between March 3 and July 2, and on as many 
dates, that no growth took place after intervals varying 
from 2 to 10 days, the exact times after which all germs 
were dead, or after no growth was observed, being 10, 7, 8, 
9, 2, and 5 days respectively while the corresponding times 
for the diffuse light were 5, 3, 5, 6, 1, and 4 days. The 
averages of these two groups of intervals stand in about the 
ratio of 7 to 4, which means that under the conditions of 
exposure adopted and the method of testing viability the 
life of tuberculosis germs was rather less than 4 days in 
diffuse room light and that in the dark their life was less 
than 7 days. But it would be very misleading to leave 
light as an agent of disinfection with the reader thus 
stated. It should be understood that direct sunshine is far 
more potent in destroying disease germs than is reflected 
light and that that from the noon sun is stronger than the 
light coming from it earlier or later in the day. Most im- 
portant of all to remember, for the direction it should give 
to practice, is the fact that even in the brightest sunshine 
the slightest shadows materially cut down its power to de- 
stroy germ life, so that under the hay and bedding of the 
stable and especially in the dung, where germs may abound, 
effectual darkness may obtain where the direct sunlight of 
noon is falling. Here is the kernel: Utilize to the fullest 
practicable extent every available agent of destruction, but 
remember that in every infected stable and home although 
millions of germs may be destroyed multitudes will escape 
and the losses will be made good from the springs of life. 
Remember, too, it is within the body, where effective dark- 
ness always prevails, that injury is done if it is powerless to 
resist, hence no amount of sunshine can compensate for the 



84 Ventilation. 

diminished bodily vigor which results from insufficient ven- 
tilation, or other food supply. 

It is important to understand something of relative in- 
tensities of the light received from the sky from different 
quarters and of that direct from the sun compared with 
that from the sky. Dr. C. G. Abbot of the Smithsonian In- 
stitution and Director of the Astro-physical Observatory, 
has determined the relative intensities of sky light coming 
from different elevations above the horizon from Mount 
Wilson at the time of clear sky in August and September 
with results given in the table below : 

Average brightness of the sky at different distances above the horizon. 

Altitude. Eelative intensity. 

0° to 10° 460 4.00 

10 to 20 210 1.82 

20 to 30 185 1.61 

30 to 40 150 1.31 

40 to 55 128 1.11 

55 to 75 122 1.06 

75 to 90 115 1.00 

This table makes it appear that windows taking light 
from near the horizon may receive nearly four times the 
amount of that coming from directly overhead supposing 
the windows vertical in the first case and horizontal in the 
second and no obstructions whatever in either instance. 
As to the relative intensities of sky light coming from the 
south, east, north or west Dr. Abbot writes as follows under 
date of Oct. 28, 1908 : 

' ' I regret that our observations on the sky have not been 
conducted excepting on Mount Wilson, and that they are 
scanty even there, so that my replies to your questions can- 
not, I fear, be very satisfactory to you. 

I feel sure that most light will be received from the sky 
if the stable windows face south (obstructions of course be- 
ing absent). East and west will be nearly alike in this re- 
spect, but in most sections west will receive more than east. 
North is least favorable. 

Less sky light will be received at high altitudes above sea 
level and at very clear localities than at low and hazy sta- 
tions. 

The horizon is much brighter than the zenith so that 



Intensity of Sky Light. 85- 

where trees and hills do not obstruct the view the windows 
would receive most light I suppose if they w^ere horizontal 
rather than* vertical in their longer dimensions. I incline 
to think that horizontal windows adapted to receive light 
from the horizon to 30° altitude with unobstructed south- 
ern exposure would receive as much as four times the light 
equally large vertical windows with north exposure and 
adapted to receive light from 30° to 90° altitude would 
admit. But this is not a computation and is not applicable 
to all latitudes and altitudes above sea level, but is only 
intended as a probable estimate to suit average conditions 
in the United States. In winter the advantage of horizon- 
tal southern windows is greater than in summer. 

As to the disinfecting qualities of the sky light at dif- 
ferent zenith distances I know nothing. It seems prob- 
able to me, however, that if any such qualities exist in 
zenith sky light they would be found in at least equal and 
probably in greater total amount (not percentage), in the 
horizon sky light. 

I do not know whether the disinfecting properties of 
light are cumulative as the photographic action is, or far 
greater if the light is very intense like the rise of temper- 
ature of a body in the focus of a lens. If the former is the 
case I should have little question that the continued action 
of sky light would be preferable to the brief action of sun- 
light. The whole sky at sea level is apt to contribute nearly 
as much light as the sun, and by far the larger proportion 
in middle northern latitudes comes from the southern half 
of the sky. 

The above opinions are presupposing a generally clear 
sky. If the sky is most of the "time cloudy, southern ex- 
posure would still be preferable but the horizon would, I 
think, cease to be the best part of the sky." 

If Dr. Abbot's views thus tentatively expressed shall be 
found correct stables and dwellings should be lighted as 
far as practicable from the south for the reason that both 
direct sunshine, in the middle north latitudes and the max- 
imum amount of sky light may thus be obtained. In the- 
eastern part of the United States, east of Kansas, the aver- 



86 



Ventilation, 



age per cent of sunshine, computed on the total possible, 
is near 56. Taking this in connection with the fact that 
generally a considerable portion of the horizon to an alti- 
tude of 10° is obstructed we are inclined to favor windows 
with their long dimension up and down. The diiference 
will be made clear from a study of Fig. 36, where it is seen 
that the point A on the floor receives sky light through the 
window E from between 20° and 50° above the horizon 
while from the window W, having half the vertical height, 
light comes in between 20° and 35°. If the lower light is 
most intense the last window will admit the most sky light, 
but if the higher light is best then the former window is to 
be preferred, from the standpoint of sky light. With the 
high window, as seen at C and B, direct sunshine must 
sweep a materially broader floor area than if it- is short. 




Fig. 36. — Influence of higlit of windows on the admission and distribu- 
tion of liglit in a building; B, C, area of direct sunstiine; heavy arc of 
circle subtends angle of diffused light falling at A. 



In low stables with wide overhanging eaves, and where 
windows are under porches, the same area of glass admits 
very materially less light, as is evident from an inspection 
of Fig. 37. The overhanging eaves at A, it will be seen, 
cut out half the direct sunshine and at the same time ma- 
terially prevent the entrance of diffused light from the sky. 
From the other side of the building, where the eave does 
not overhang so far, both the quantity of direct and of re- 



Efficiency of Windows. 



87 



fleeted light are seen to be materially increased over that 
entering the opposite window, as shown by the length of 




Fig. 37. — Effect of overhanging eaves and porches in reducing the effi- 
ciency of windows. 

the direct sunshine areas D and E and by the size of the 
angles of diffused light falling at the point C. 

It should be remembered too that where the walls of a 
building are thick relatively larger windows are required 
to secure the entrance of the same amount of light, the fact 
being made clear by a study of Fig. 38. The window at F, 




Fig. 38.— Showing the effect of thickness of wall in reducing the effi- 

ciency of windows. 

four feet high in a wall one and a half feet thick, has its 
direct sunshine efficiency reduced nearly one-fifth by the 
thickness of the wall, as shown by the area marked H,. 



SS Ventilation. 

** sunshine cut out/' with a width for this window of three 
feet, as shown at A, and with a thickness of wall of 18 in- 
ches, the angle at which sky light may enter is reduced 
from 180-^^ to 128^,- while a wall of half this thickness re- 
duces the angle for dithised li^ht only to 150^. AYith 
larger windows for the same thickness of wall the percent- 
age loss of efficiency is less. In the case of direct sunshine 
the drawing represents the smallest possible reduction with 
the sunlight entering at the angle represented, the building 
l)eing supposed to face the south with the sun at noon. 
At any time before or after noon, with the same altitude of 
the sun, a still greater reduction than that represented 
must take place. 

VENTILATION OF DWELLINGS. 

It is safe to say that before the close of another hundred 
years a very large proportion of the dwellings now in use 
will have been entirely rebuilt or extensively remodeled 
and that it is now none too early to begin a campaign of 
education which shall lead to the rebuilding or remodelling 
of those dwellings along lines which will make them thor- 
oughly sanitary, convenient, pleasant and capable of being 
economically maintained in all of the ways which can con- 
tribute to substantial home comfort and character building. 

It is also safe to say that at least two more generations 
will be compelled to grow up in the dwellings now in use 
but which are far less sanitary, from the standpoint of ade- 
quate ventilation than were those of the grandparents of 
the children now sixty. Then, in whatever other ways 
those homes may have been deficient, there was continually 
moving through them an abundance of undiluted and un- 
polluted air. The wide-open throat of the great fireplace 
of those days, which never could be closed, Avas everlast- 
ingly sucking out of the few rooms and in through the 
chinks in the wall, great volumes of air such as few people 
living in modern dwellings can realize. Today, with win- 
dows double; with walls sheated inside and out, sided, 
plastered and papered, on retiring we close everything 



Ventilation of Dwellings. 89 

tight, even to the heater and kitchen range, and wake the 
next morning from troubled slumber hoping that, whatever 
else may not have been for the best, we have at least saved 
a little of the $9.50 per ton coal. Clearly if the two gener- 
ations which must dwell in the old homes can be led and 
helped to better conditions of living in them great present 
and future gain will result. The vast throng of victims 
annually and prematurely wilting and fading away before 
the dreaded white plague meet disaster, not so much be- 
cause of the great numbers and wide-spread distribution of 
the disease germs, as because of the terrible prevalence of 
such living conditions for cattle and people alike as convert 
the weak among them into hotbeds for the breeding of 
tuberculosis germs. Disease-germ-bearing milk is only one 
of a thousand vehicles by which these germs are spread and 
helped to gain a new foothold. If we shall ever succeed in 
greatly reducing the numbers of its victims it must be 
through fortifying the individual, rendering him capable 
of resisting the development of the disease germs even if 
they are introduced into the system, and this must come 
through more wholesome conditions and habits of living. 

It cannot be too forcibly impressed upon the manage- 
ment of households that when one's duties are such th^>t 
much of the time is spent in the open air, or that one is out 
and in frequently, the consequences that follow inadequate 
ventilation are likely to be far less serious than upon those 
confined more exclusively to the house. It should be re- 
membered too that the person whose system has just been 
thoroughly renovated by breathing an abundance of fresh 
air is less sensitive to, except for the moment, and can 
safely endure, degrees of air pollution which may be 
oppressive and dangerous to those continually confined to 
inadequately ventilated rooms. And so it often happens 
that the menfolk of the farm are living fairly well, while 
the women in the same home may be suffering severely, 
-especially during the winter, for lack of proper ventilation. 
Thought and judgment, therefore, exercised in the house as 
well as in the barn, is necessary. 



90 , Ventilation, 



Ventilation of Houses Already Built. 

When the heating of the house is by means of stoves 
placed in the living rooms a certain amount of ventilation 
is secured through the direct action of the stove, for all of 
the air which enters the stove and leaves the room through 
the chimney is drawn into the house, through chinks in the 
walls where no special provision for entrance is made, and 
so long as the draft of the stove is open there may be suffi- 
cient ventilation for the time but so soon as the draft is 
closed and air ceases to escape through the stove, inade- 
quate ventilation is likely to result. Suppose it is in the 
evening and five of the family are gathered about the table 
in a room 15 by 15, with a 9-foot. ceiling and that they are 
using a lamp whose power to vitiate the air is equal to that 
of 10 candles such as used in Fig. 13. There would then 
be a consumption of air in the room equal in amount to 
that demanded by nine or ten people. We have found the 
ordinary student-lamp to burn kerosene at the rate of 38.4 
grams per hour and this demands oxygen equivalent to 
more than six people, so that it is safe to say that, with five 
people and such a lamp, air is needed for the equivalent of 
ten people, and this demands an air movement, to maintain 
the standard of purity which we have assumed as possibly 
permissible for dairy stables, equal to 5,370 cubic feet per 
hour, which requires the room to be emptied of all its air 
and refilled once about every 22.6 minutes. It will be 
readily seen from this statement of fact that whenever the 
room becomes a little too warm, so that the drafts in the 
stove are all closed, such a room, not otherwise ventilated, 
would very soon become unsanitary from the standpoint of 
pure air. Indeed, with no interchange of air, in one hour 
nearly one-tenth of the whole air of the room would have 
been used once, and in once-breathed air we have seen the 
candle extinguished. 

Let us see now what the stove can do for us in the way 
of ventilation when the drafts are open. Suppose the 



Combined Heater and Ventilator. 91 

chimney is 30 feet high and the air in the chimney is main- 
tained at a temperature 50 degrees above that of the air 
outside'. From the table, page 56, the theoretical flow 
through a one-foot square chimney 30 feet high is 50,472 
cubic feet per hour. With half this efficiency, to allow for 
resistances to be overcome, and taking the cross-section of 
the 6-inch stovepipe through which the air must all go, at 
. 2 of a square foot, the air movement which could be main- 
tained is at the rate of 5,047 cubic feet per hour, which is a 
little less than 5,370 cubic feet, the movement we have as- 
sumed as possibly permissible. This reasoning and calcu- 
lation makes it clear that whenever a room thus ventilated 
has the drafts in the heater closed the necessary air move- 
ment must at once fall below good living conditions and 
hence that some provision ought to be made for keeping up 
the air supply whenever the heater is not running with 
open drafts. There is often a check-damper in the stove- 
pipe or stove which may be opened when the drafts are 
closed and so partly, at least, keep up the air movement. 
Such openings, however, as usually placed, are wasteful of 
heat because they throw out of the room only the warmest 
air. To economically use the room heater as a ventilating 
device there ought to be attached to the stovepipe, as rep- 
resented at C in Fig. 39, a section extending down to near 
the floor level, provided with a close-fitting damper, so that 
whenever the drafts are closed in the stove the damper in 
the ventilating section may be opened, and thus keep up 
the air circulation, drawing out of the room only the cold- 
est air it contains. Here, then, is a simple arrangement by 
which many a poorly ventilated home may have its sani- 
tary conditions very materially improved, at a trifling ex- 
pense when compared with the advantages gained. If the 
room to be ventilated is tightly constructed and if air can- 
not be borrowed from another unoccupied room by leaving 
the door ajar, there is no reason why fresh air intakes may 
not be provided on the same plan as has been illustrated for 
dairy stables in Figs. 31-32, pp. 72-74, and which is rep- 
resented at AAAA, BB, in Fig. 39. In providing such in- 



92 



Ventilation. 



takes it is only necessary to make openings through the sid- 
ing, as represented at A, between pairs of studding, cover- 
ing them with one-eighth inch mesh galvanized wire net- 
ting, and make corresponding openings just under the 
ceiling at the same pair of studding, covering these with 
white enameled 4 by 12-inch register faces. 




Pig. 39.— Improvised ventilation system for an ordinary dwelling already 

built. 

The proper course to take in installing such a ventilation 
system is to modify the heater so that air may be removed 
from the floor level as already described. If it is then 
found that an air change of sufficient rapidity takes place, 
this being made possible through unintentional openings in 
the wall, the desired result has been attained and the in- 
takes need not be provided. It may be that a sleeping room 
:' situated as represented in the illustration, through which 
the stovepipe passes. If so it is a simple matter to attach 
.a radiator to the pipe and thus without extra expense ma- 



Heating ivith Warm Air and Ventilation 93 

terially warm the room and improve its ventilation if only 
a ventilating fine is installed as indicated at D. In this 
case we have assumed that there is a partition and that the 
space between a pair of studding may be opened just above 
the baseboard and covered with a white enameled register 
face, or better still, a register which may be opened and 
closed, and then open this space into the attic or, what 
would be much better, extend up through the roof a six- 
inch galvanized iron pipe, connecting this with, or extend- 
ing it down into, the space between the studding leading 
to the ventilating register. With such an arrangement, 
with the fresh air intakes indicated in the figure and with 
the radiator as shown, we have an ideal sleeping room or, 
if the heater below is large and the room above small and 
warmly built, it may be a comfortable sitting room with- 
out the expense of additional heat. 

Dwellings that are heated with hot air furnaces, if they 
are thus sufficiently warmed, are usually amply ventilated 
so long as the warm air is being forced in, unless the faulty 
arrangement has been adopted of returning the air from 
the heated rooms to the furnace to be revolved over and 
over again. Such a system is very bad and should never 
be used unless it be in faultily constructed houses where 
there is excessive air leakage through the walls or in windy 
weather when the temperature is excessively low. In 
steam-heated houses and in those heated with hot water by 
means of radiators distributed in the rooms to be heated the 
ventilation may be, and usually is, extremely deficient, 
much more so than with stove-heated rooms, for the reason 
that with these systems of heating there may be provision 
neither for air to enter nor leave the room, dependence be- 
ing wholly upon leakage through the walls or upon the 
opening of windows and doors. In houses thus heated some 
means should be adopted for drawing the air out of the 
rooms at the floor IcA^el, even if nothing better than the 
plan suggested for the second floor in Fig. 39 at D. Fresh 
air intakes should also be provided and if possible these 
should be so placed that the air may be admitted at the 



94 Ventilation. 

ceiling directly above the radiators, of course admitting the 
air from low down outside, as at A B, Fig. 39. "When the 
fresh air intakes are thus located the currents of warm air 
rising from the radiators at once mingle with the fresh 
air entering, so that this is immediately and directly tem- 
pered. Of course very many variations will occur in mak- 
ing the necessary provisions for the ventilation of houses 
already built but enough has been said to permit such 
adaptations as may be called for. 

Warming and Ventilation for New and Remodeled Houses. 

As has been earlier said the real problem with which we 
have here to deal is, how nearly can we maintain the air of 
dwellings at the normal out of door fresh air purity with 
practicable economy. Accepting this statement as correct 
it follows that if pure air itself can be economically warmed 
and used as the medium for distributing heat through the 
house it by all means should be used, rather than water, as 
such, or in the form of steam. All but two of the twenty- 
eight years of our home-making have been spent in two 
eight-room houses, each with two stories with a cellar and a 
floored attic, full size. Both were of wood with walls of 
2 by 4 studding covered with tongued and grooved fencing 
inside and out; papered and sided outside and lathed and 
plastered inside. The space between every pair of studding 
was ceiled at each of the three floors to prevent the circula- 
tion of air currents between rooms and attic due to leakage 
through walls and ceiling. The windows were all made 
with single sash but double glazed, except three in the sec- 
ond house, which were of plate glass. Each house has a 
single chimney beginning in the cellar, with three flues, the 
central one 12 by 12 inches, for the furnace and kitchen 
range, and two, one on each side, 8 by 12 inches for ventila- 
tion. Both houses are warmed with hot air, the whole lower 
floor except the front hall being maintained at 64° to 68° 
eighteen hours per day. Plants have been grown continu- 
ously in bay windows and on window brackets in both 



Heating with Warm Air and Ventilation. 95 

houses and these have never been frosted, they have never 
been moved from the brackets to prevent freezing, the only 
precaution taken being to draw the curtains, and the fur- 
nace has never received attention nights after retiring, 
usually about 11 p. m. The first house was warmed more 
than fifteen years with a single cast-iron box stove, using 
four-foot wood, which was provided with a drum of sheet- 
iron and bricked in like a furnace. The second house is 
warmed with a No. 10 Economy furnace having a metal 
shield and using coal. The fuel bill for furnace and kitchen 
range in the first house ranged from $55 to $75 per annum, 
In the second house it has ranged from $64 in the earliei 
years, increasing with the price of coal, to $95.50 in 1908, 
using hard coal with some wood in the range, and gas coke 
at $6.75 per ton, and ''buckwheat" coal at $6.50 per ton, 
burned together, in the furnace ; ' ' chestnut " at $9 per ton 
for the kitchen range. From this practical experience, cov- 
ering a continuous quarter century of Wisconsin climate 
we feel justified in saying that in a warm, well-constructed 
house it is entirely practicable to economically warm an 
eight-room dwelling by distributing the heat with warm 
air, which at the same time serves the purpose of thorough 
ventilation. We think we are also justified in saying that 
if there is ever an investment that pays it is the little extra 
required to build a house for a cold climate" Avarm, well and 
thoroughly ventilated, if your own family is to live in it. 
The saving in fuel alone is high interest on the extra money 
invested and you get the healthful conditions and comfort 
free. But we would not advise hot air warming for a 
house poorly constructed. 

Rooms provided with fire-places may be well ventilated 
but seldom economically warmed. Steam and hot water are 
well adapted to heating all types of dwellings but the cost 
of installation and that of maintenance, excepting for fuel, 
is relatively high. Good ventilation may be provided with 
both hot water and steam but it is seldom that anything 
specific is done along this line and when proper ventilation 
is added the difference in cost of installation over warm- 



96 Ventilation. 

ing with air becomes still greater. The perfect heating of 
a house with warm air is only made possible by first pro 
viding adequate ventilation because, before the warm air 
can enter a room the cold air must first escape. With both 
hot water and steam the house is most easily and cheaply 
warmed when there is the least ventilation. 

We shall consider first the warm air method of heating 
and ventilation because, for homes of moderate cost, and 
especially in the country, distant from plumbing facilities, 
this method is more readily managed as well as more 
cheaply installed; and because such a dwelling must then 
be thoroughly ventilated if it is warmed. The first require- 
ment is a warm, close construction and, everything consid- 
ered, the cheapest thoroughly warm construction is a frame 
house sheated inside and out with low-grade hemlock, hav- 
ing the outer layer of sheating covered with the cheapest 
grade of roofing tin or a very light weight of galvanized 
iron carefully and closely nailed with edges slightly over- 
lapping to thoroughly exclude the air. Walls so built may 
then be treated outside and in with any desired finish to 
suit the taste. The two thicknesses of %-inch dry lumber 
forming air spaces between the studding, even if the boards 
are not matched or tongued and grooved, so long as the 
metal is used to thoroughly stop air circulation, will give 
a far warmer wall than building papers for the reason that 
the soft wood is, both because of its texture and its greater 
thickness, superior as an insulator to the building papers. 

All spaces between studding should be thoroughly closed 
at the level of the three floors, which may be readily and 
best done by fitting in between the studding rough boards 
and then filling in with about six inches of a lean mortar, 
or concrete, which will thoroughly close the spaces and 
make the walls vermin-proof. Storm sash, fitting closely, 
on all but plate glass windows, should be provided. Farm 
houses should all have a cellar and floored attic the full size 
of the house. Both spaces are needed for both service and 
warmth and the extra cost, considering what is gained, 
should not lead to their omission. A good furnace of am 



Heating with Warm Air and Ventilation. 



97 



In at ceiling 




From/\ furnace 



f loor 



Fig. 40. — Method of introducing warmed air from furnace at the ceiling 
and of removing the fouled, exhausted and cooled air from the floor, 
both through the same space in the partition. 



98 



Ventilation. ' 



[ill 



^ 



pie size, with conveniences for storing fuel, should occupy 
the basement, the location being chosen with special refer- 
ence to the most direct connection between the furnace and 
the rooms to be heated. Both the warmed, fresh air and 
Attic the fouled, depleted and cooled air 
may be most advantageously con- 
veyed through the partitions in the 
manner represented in Fig. 40, the 
warm air, as represented by the long 
arrow, passing from the furnace 
through the flue and entering the 
room at the level of the ceiling while 
a corresponding volume is forced out 
from the floor level as shown by the 
other two arrows. 
"Seconal floor ^^ most houses constructed in the 
=^=- manner described it will only be nec- 
essary for the ventilating flues to ex- 
tend into the attic ventilating all 
rooms into this space which then 
makes an excellent clothes drying 
room for blustering and stormy 
weather. The air may pass either 
directly into the attic from each 
room, or it may be passed into the 
room above, thus warming it indi- 
rectly in the manner represented in 
Fig. 41. In this case the warmed 
air flue extends to the level of the 
ceiling of the' room on the second 
floor where it is closed, the air leav- 
ing by an opening at the ceiling of 
the first floor. With this arrange- 
Fig. 41.— Method of ventii- ment forccd ventilation for the first 
into an upper one. floor is provided. The flue' being all 
the time filled with warm air heats the surrounding air 
in the same space thus giving a column 18 or 20 feet long 
to aid in producing a draft out of the lower room. The 



^^ Warned 
f—* Oft 

I 



« Coo/ed 

Fir<st floor 



Basement 
From furnace 



Heating with Warm Air and Ventilation. 



99 



upper room may thus be largely or wholly warmed without 
extra heat. To secure this result the space between the pair 
of studding is made sufficiently large, as seen in Fig. 40, to 
contain the warmed air flue and provide ample room to act 

H 



lit 



Attic 



War me of 
air 



w 



1". 



Cool&cl 
~'air 



Se end floor 



as a ventilator. Before lathing the 
partition the hot air flue is installed 
and the space closed by covering 
with roofing tin or a light weight of 
galvanized iron. This makes a safe 
arrangement and permits the hot air 
flue to have a single wall. At the 
same time a tight-walled ventilating 
shaft is provided for the lower room. 
With this arrangement it is neces- 
sary to provide ventilation for the 
upper room. This may be done by 
opening into the space between an- 
other pair of studding letting it dis- 
charge into the attic. If more heat 
is desired for the upper room a plan 
similar to that represented in Fig. 
42 may be adopted, which is an ex- 
tension of the principle of Fig. 41. 

If only direct heating and direct 
ventilation are desired then the 
method A^dll be essentially the same 
as in Fig. 41, the hot air flue extend- 
ing to the attic floor in either case' so 
as to secure the maximum forcing ef- 
fect. The chief objection to the 
methods of warming and ventilating 
the house; as has been described is 
the comparatively small motive power 
for ventilation at times when there 
is no fire in the furnace. It is true, 
howpvpf . thRt at such times the house 
is more or less thrown open through doors and windows. 

Another method for direct heating and ventilation is 
represented in Fig. 43 where there is a central chimney of 



F/VvSt flaoir 



Basement 
Fromfutnace 

Fig. 43.— Method of 
heatinar upper room 
and ventilating' into 
the attic. 



100 



Ventilation. 



brick, with flue lining, surrounded with a ventilating shaft 
made of galvanized iron nailed directly to the studding be- 
fore lathing. In this diagram four rooms directly adjoin- 
ing the chimney are represented as being ventilated at one 
floor level. Distant rooms on the same floor may be con- 
nected with the same flue by leading a fouled air duct under 
the floor cut into the ends of the joists under the partition, 
or in the space between two joists if they extend in the 
right direction. If it is so desired these ventilators may be 
finished in imitation of fire places. 




Fig. 43.— \ entilating flue of galvanized iron surrounding the chimney and 
utilizing the warmth of the smoke flue to force the draft in the ven- 
tilator. A flue lining is used inside the brick. 

If so desired the ventilating flue may begin at the sec- 
ond floor or even at the attic floor when it is desired to 
warm the upper rooms with the exhaust air from the lower 
ones. Such a plan, however, cannot derive as much advan- 
tage from the warmth of the chimney. 

If it is desired to heat with either steam or with hot 
water some system of ventilation should by all means be in- 
stalled at the same time and this can be done without dif- 
ficulty and without greatly increasing the cost as will be 
readily seen from a study of Fig. 44. In this type of 
house warming the radiators should be placed under the 
fresh air intakes where the warmed air will rise where the 
cold air enters and falls. 

When fresh air intakes are provided for each room to be 
occupied and ventilators are provided in some one of the 



Ventilation with Steam and Hot Water Heat. 101 

ways already described and illustrated ideally sanitary 
homes will be provided so far ias fresh air is concerned. 
The air may exhaust through a fireplace, thrpugh a shaft 




Fig. 44. — Ventilation of a house warmed with steam or with hot water. 

built about the chimney as illustrated in Fig. 43, or by 
means of flues placed in the partitions and exhausting into 
the attic or directly through the roof. 

In the next illustration is shown a type of house which 
is extremely well designed to meet the needs and comforts 
of country homes. It may be made larger or smaller; the 
verandas and decorations may be altered to suit the taste 
or expense ; for a smaller house the kitchen may be omitted 
and one of the other rooms adapted to this purpose. It is 
a type which lends itself well to economy of construction, 
to economy of heating, and it may be well ventilated by 
any system of heating if proper attention is given to the 
matter when laying out its construction. 



102 



Ventilation. 








.Second ploojr^ 



Tigs. 45 and 46.— Elevation and floor-plan of house readily warmed and 

ventilated. 



HEATING AND VENTUjATION OF RURAL SCHOOL-HOUSES AND 

CHURCHES. 

Now that concrete construction has been so far perfected 
and cheapened it appears to the writer that we are in posi- 
tion to build all new country school-houses and churches 
in a manner which will permit of their being both ideally- 
warmed and thoroughly ventilated. To have conditions 
right both school and church should have thoroughly warm 
:floors and they should have a moderately warm atmosphere 



Warming and Ventilation for Rural Schools. 103^ 



which is being rapidly and continuously changed. To- 
secure these ends it is necessary to remove the heater to a 
basement and then permit none of the air which comes in 
contact with it to become a part of the air supply. This^ 




Fig. 47.— Warming and ventilation for a country sctiool or church. 

in our judgment, may be readily done and more econom- 
ically than warming with poor ventilation is now accom- 
plished. 

Describing first a country school-house built along these 
lines, as represented in Fig. 47, there is constructed a mon- 
olithic concrete basement, including the first floor, using in 
the walls, for warmth, hollow building tile bedded in the 
concrete mass. These tile are cheaper than the concrete- 



104 Ventilation. 

and they offer the most expeditious way of securing a hol- 
low wall. On the walls is constructed a reinforced con- 
^Tete ceiling and floor, the ceiling built first and covered 
closely with a layer of hollow tile carefully laid in series 
so as to form continuous air ducts through which to circu- 
late heated air for the purpose of warming the floor and 
through it, as a radiator, the room above. A cement floor is 
then laid over the tile. 

Across the center of the floor-ceiling the tile would be 
omitted over a strip three or more feet wide forming a 
broad duct into which the heater casing communicates so 
as to flood all of the tile with hot air and thus warm the 
floor. At the two ends of the building a similar but nar- 
rower duct is formed which permits the heated air to es- 
cape and return to the heater, thus providing means for the 
continuous circulation of the same mass of air on the prin- 
ciple of the circulation of water or steam. The heater 
room should have tight walls except near the floor so as to 
confime a column of heated air, this being the motive power 
for maintaining the circulation. The air then enters the 
heater chamber at C, Fig. 47, passing to the ceiling to be 
distributed through the various channels and is again re- 
turned to repeat the circuit indefinitely. 

The room to be warmed and ventilated above is closely 
constructed and finished with a ceiling provided with open- 
ings AA through which the air may enter from the outside 
as indicated by the arrows AA AA ; the air rising between 
the studding and along the spaces formed by the joists. 
The floor above these joists must be very tight and warm. 
"The air everywhere in contact with the floor is warmed and 
forced to circulate as it would be if steam or hot water rad- 
iators were used. 

The chimney is best made of suitable size wrought iron 
pipe or boiler tubing or else of a heavy weight of sheet iron 
riveted and this should occupy the center of the ventilating 
shaft, which is best made of galvanized sheet iron. With 
this construction, the air entering the shaft from the room 
at BB. is forced out by the waste heat of the smoke flue ; and 



Warming and Ventilation for Rural Schools. 105 

fresh air directly from outside is thereby continuously 
drawn in through the intakes AA. In the illustration E 
suggests a way in which a hot air radiator may be installed 
furnishing a convenience for hand warming if desired; 
here warm air simply circulates from and to the furnace 
and does not escape into the school room. It may be made 
in cement. 

The great advantage of heating from the basement in 
some manner is that it insures a thoroughly w^arm floor. 
When the feet are adequately and continuously warm a lower 
surrounding air temperature is admissible and this makes it 
quite certain that a larger air circulation will be maintained 
which is the important point in every school room. It fol- 
lows, therefore, that even if the heater is not placed in the 
basement there should be a good cellar under the whole 
floor with warm waUs and deep enough not to freeze and 
to serve as a store room for kindling and fuel and to help 
keep the floor more comfortable to the feet. If a cellar will 
not be built then a damp-proof cement floor laid directly on 
the ground, which may be covered with a layer of boards 
or linoleum if desired, is far warmer and more sanitary as 
well as enduring, than many of those now in use. 

If the heater is in the school room, its proper place is 
central on the floor but near the entrance. It should be 
surrounded on three sides with a metal shield, open toward 
the door, to cut off direct radiation from the children. The 
smoke flue should rise straight out through the roof, and it 
should be surrounded by the ventilating flue as represented 
in Fig. 48, drawing out the fouled air at the floor level and 
from behind the screen at A. The fresh air should be in- 
troduced through the ceiling rising through the walls from 
low down outside, Fig. 47, discharging largely in the front 
of the room and over the heater where it may mingle di- 
rectly with the warmest air; or it may be taken directly 
down through the roof in the manner shown at BB where 
the duct is provided with a revolving cowl at the top, to 
utilize fully the wind pressure, and with an air trap at the 
lower end to prevent the escape of warm air. In still an- 



106 



Ventilation. 



other way the air may be let in beneath the floor and directly 
up under the stove and inside the jacket. The advantage of 
the method of taking fresh air represented in Fig. 48 is 




Fig. 48.— Ventilation of school room which must contain the heater. 

that when there is little or no fire in the heater to force a 
draft, the combined effect of wind pressure and wind suc- 
tion may be utilized. A damper in the ventilating flue at 
C permits the amount of air moving to be controlled at any 
time. 



Ventilation of Stables. 107 



Yentilation of Dairy Stables. ' 

In the details of stable ventilation there must be almost 
endless variation to meet individual conditions. Notwith- 
standing this, the principles governing construction are few 
and have already been stated in general terms. Because the 
motive power usually available in stable ventilation is both 
small and variable in intensity it is of the highest impor- 
tance that strict attention be given to all essential details of 
construction necessary to adequate efficiency. 

The one detail of paramount importance in every system 
of stable ventilation is the outtake flue. It is, in function, 
nothing more than a chimney ,- it should be nothing less than 
one of the best type, barring the single feature that it need 
not be fire-proof. Whatever is counted essential in a good 
chimney must be held even more essential to a good stable 
ventilating flue ; and whatever would be ruled out of the 
construction of a good chimney must be more scrupulously 
excluded here, and for the simple reason that the motive 
power at best is small when compared with that available 
in most good chimneys. The walls of the outtake should be 
so made as to be and to remain permanently air-tight except 
where openings are provided. This feature is essential in 
order that only air from the space to be ventilated shall con- 
tribute to the current passing through. In practice many 
outtakes have been constructed so openly, above the stable 
to be served, that their efficiency is thereby greatly im- 
paired. Next in importance is an ample cross-section, uni- 
formly so throughout its length. If the outtake is con- 
stricted at any point the smallest section determines its ca- 
pacity. Reducing the diameter of a cylindrical flue one- 
half makes the pressure necessary to force a given volume 
of air through nearly four-fold, while doubling the diameter 
permits one-fourth the pressure to do the work. The out- 
take which is circular in cross-section or square is to be pre- 
ferred to one long and narrow, because the wall surface for 
cooling the air and for friction is relatively materially less 



108 



Ventilation. 



and this means less loss of pressure and hence greater flow 
when the motive power is small. The oblong section may be 
chosen if conveniences require it, but then the area should 
be made relatively greater. The motive power for ventila- 
tion due to temperature differences increases with the hight, 
and the suctional effect of the wind does also, but the loss of 




Fig. 49.— Showing manner of constructing outtal^e flue, using 2x4's for 
corners and galvanized iron for walls, covered with wood If greater 
warmth is Important. 



power due to friction increases with the length and with 
bends. The outtake should, therefore, be free from angles 
wherever practicable. 

Galvanized iron is the best available material with which 
to construct the walls of outtake flues, and they are most 
simply made in the manner shown in Fig. 49. The sheets of 
metal may be obtained in widths from 24" to 36" and in 
lengths of 8' or 10'. The metal should be nailed closely 
as represented in the upper part of the figure, using small 
galvanized wire nails to avoid rusting out. If the flue is in 
an exposed situation it may be covered with wood, as shown 



Construction of Outtakes and Intakes. 



109 



in the lower part of the cut, to lessen the cooling of the air 
during its passage, or the flue may be made larger to com- 
pensate for loss of power through loss of heat. Where the 
ends of sheets meet pieces should be cut in between the up- 
rights into which to closely nail the ends, overlapping about 
an inch. 











, 


s » 












lii 






<?. 










,.,: 






f 




i'l 


•1 








» « 


^. 


1 










/ 


4 




/ 


■9. 


r~ 



Fig. 50.— Several types of intakes. 1, utilizes 
space between studding; 2, made ot, galvan- 
ized iron shaped as at a; 3, constructed in 
masonry wall; 4, for basement stable al- 
ready built; 5, utilizing space between 
double windows. 



At present prices the metal is cheaper than paper for the 
reason that only a heavy grade of acid and water proof 
variety is permissible and this can only safely be used be- 
tween two layers of tongued and grooved boards. "Without 
this precaution the paper will warp and tear itself loose and 
it is liable in any case to disintegrate in time, leaving leaks 
between the boards. 

The construction of the intakes is not a matter of such 
critical importance. Almost any sort of flue will answer. 
They should be numerous, well distributed on all sides of the 
stable if practicable, and, in order that they may trap the 
escape of the warm air of the stable, the outside opening 
should be three or more feet below the inlet. Their aggre- 
gate cross-section should equal if not exceed that of the out- 



110 Yentilation, 

takes, unless the stable has an open construction, for the 
reason that air can continuously leave the stable no faster 
than it can enter. Small intakes distributed at intervals of 
about 12 feet are to be preferred to large ones, there being 
then a better commingling of the cold with the warm air 
and less danger of cold drafts. 



Yentilation of Dairy Stables. 

In January, 1889, we received a request to design a barn 
for a dairy farm which would accommodate 80 cows and 10 ' 
horses and which would permit of driving behind the cows 
in cleaning and in front in feeding. A silo, granary and 
storage space for roughage sufficient for all the stock were 
desired and it was specified that all should be under one 
roof, every thing conveniently accessible and not relatively 
expensive. The barn was built during the summer of the 
same year on the farm of Mr. C. E. King, Whitewater, Wis., 
to accommodate 98 cows, and was the first structure to con- 
tain the ventilation system for stables here described. In 
describing the bam for the Seventh Annual Report of the 
Wis. Agr. Exp. "Station we said: Whatever conveniences 
a barn may contain these should in no way interfere with 
the best performance of the animals housed. It should be 
so built that the heat given off by the animals housed shall 
be sufficient to maintain the best stable temperature and at 
the same time admit of ample ventilation. It should ad- 
mit the necessary amount of light to all the animals and 
be so constructed as to reduce care-taking to a minimum. 

The barn as erected is represented in Fig. 51 and was of 
the cylindrical type, 92 feet in diameter, two stories, and 
costing at that time, with the average price of lumber $15 
per thousand, a little less than $2,400, not including the 
board of the carpenters. The manner in which the ventila- 
tion was secured is shown in Fig. -52 where the 32 spaces 
between the studding in the walls of the silo, 34 feet high, 

/ 
/ 
/ 



Ventilation of Dairy Stables. 



Ill 



are utilized as outtakes, having an aggregate cross-section 
of 35 square feet. Here, not only are these outtakes cen- 




Fig. 



51.— First barn in which the King system of ventilation was in- 
stalled, in 1889. 



trally located in the warmest portion of the barn with the 
cows grouped about them, but the warmth of the inner walls 
of the flues, maintained by the heating of the silage, is 




Pig. 52.— Showing cows arranged in two rows centrally nhout -Mirrakes 
in the entire circumference of the silo, and with intakes for fresh 
air between every fourth pair of studding in the wall. 



112 



Ventilation. 



utilized as a constant motive power to force the air move- 
ment through them. Intakes for fresh air are provided be- 
tween every fourth pair of studding around the entire cir- 
cumference of the barn. By this arrangement there is se- 




fSllliliittWlli^lilSfi^tfttli^te 



Fig. 53.— Showing the inverted-Y type of outtake used in the dairy barn 
at Wisconsin Agr. Exp. Station. A A A is the outtake flue; C. C. 
provisions for cooling stable and reinforcing the draft. Intakes tor 
fresh air at ceiling represented at B. 

cured a continuous flow of fresh air in at the ceiling of the 
stable uniformly past every animal while the fouled and im- 
poverished air is at the same time being drawn off at the 
floor level. A thoroughly adequate and continuous air move- 
ment through the stable is thus secured without extra cost 
of construction. 



Ventilation of Dairy Stahles. 



113 



The ventilation system installed in the dairy bam of the 
Wisconsin Agr. Exp. Station, which accommodates 38 cows, 
is represented in Fig. 53. In this case the outtake is a 
single central shaft in the shape of an inverted Y as seen 




Fig. 54.— Showing a pair of U-shaped outtakes adapted to stables for 60 
takes; C ceiling register in a cross-arm joining the two sides of the 
to 80 cows. A A A A A are the two outtakes; B B B B are the In- 
outtake. 

at AAA with a small outtake, C, opening at the ceiling for 
Tise in conjunction with the other registers C to be opened 
only during still weather when the stable is too warm or the 
movement of air too slow. The fresh air intakes, shown at 
B by the series of small rectangles with arrows, are 24 in 
number, each 4x12 inches, the air entering just above the 
sill outside, and rising between as many pairs of studding. 
A more effective arrangement for the outtakes is repre- 
8 



114 



Ventilation. 



sented in Fig. 54, which shows two U-shaped flues rising 
from just behind the manger between two cows in a stable 
adapted to 60 or 80 cows, seen at AAAAA, with a ceiling 
register at C for use when the stable is too warm and to re- 
inforce the draft when needful. For 20 cows and for 40, 





pAj^^^^^^^^^^^^^^^^^^^, 



Pig. 55.— Showing single straight-away outtakes wliicli avoid all angles 
and render possible the strongest draft. 

one of these U-shaped outtakes would answer, located near 
the center of the stable. 

A still better and perhaps the best practicable arrange- 
ment of the outtakes is represented in Fig. 55 where each 
shaft is straight and rises directly through the roof and 
above the level of the ridge to be fully out of the zone of air 
currents which tend to produce down drafts. 

In the next illustration the outtakes are straight but oe- 



Ventilation of Dairy Stahles. 



115 



cupy positions against the outer walls. Here they are less 
in the way but they must be projected farther above the 
roof and are more unsightly as well as being where the ani- 
mal heat is less efficient. In barns already built, and es- 
pecially if the animals are few and a cupola exists, this plan 
may be safely adopted with the modification that the out- 
takes may be carried up to the roof inside and allowed to 
stop there or be turned toward or to the cupola. 




Fig. 56.— Showing straiglit-away outtakes placed against the wall. 

In Fig. 57 the arrangement differs from that of Fig. 55 
in having the lower ends of the outtakes against the outer 
wall, thus removing them from between the cows. There is 
another partial advantage to offset the loss due to greater 
length and angles. If the under face of the outtake along 
the ceiling is made of galvanized iron the warmest air of the 
stable will come continually against it and thus keep it warm 
to assist in forcing the draft. 

Where there is a lean-to stable, as represented in Fig. 58, 



116 



Ventilation. 



the outtake may be constructed inside the main barn and 
terminated as represented, or it may be carried under the 
roof to the cupola or to the ridge. If only a few, animals are 




Pig. 57. — Showing manner of placing only the lower ends of the out- 
takes against the outer walls. 

to be supplied the flue may be made relatively large in cross- 
section and terminated in the main barn just under the 
roof. 

In barns already built without special provision for ven- 
tilation it may be possible to utilize one or more of the hay 
chutes, if they exist, by extending them to the floor, as sug- 
gested in Fig. 59, to prevent the loss of air at the ceiling. 
Lifting or swinging doors may then be provided to be al- 
ways closed except when the hay is being put down. 



Ventilation of Dairy Stables. 



IIT 




jijg 58.— Showing method of ventilating a lean-to. 




Fig. 59.— Showing method of utilizing a hay chute as an outtake^ 



118 



Ventilation. 



The provisions for taking fresh air into the stable 
wherever the walls are hollow and rise four or more feet 
above the ground have been sufficiently illustrated in pre- 
ceding figures. In stables having solid masonry walls al- 
ready constructed the fresh air intakes may be made in the 
-manner illustrated in Fig. 60 where an intake flue is shown 







'^t^^if^d^^^M^MT^MfimT^M^f^ismMml^^ 



Fig. 60. — Showing two methods of admitting fresh air to basement 
stable C and D. The two hay chutes and the small ceiling ventilator 
are not intended to illustrate proper outtakes. 

^t C, the large arrow indicating the course of the air cur- 
rent in entering the stable. Here the space between a pair 
of studding is closed off at a hight of 4 or 5 feet and in it 
is inserted a light tin 10 inch pipe flattened to 4 inches and 
inserted in an opening through the stable ceiling. The 
space is then ceiled up and a 4-inch opening cut in the out- 
side wall about the length of the long diameter of the tin 
flue, for the entrance of air. The number and distribution 
of these should be the same as in the case of the ordinary 
intakes. 



Area of Crf>ss-section of Ventilating Flues. 119 

On the left side of the figure is illustrated another way 
of providing intakes. The space between a pair of stud- 
ding is closed at the proper hight and all but the upper 
portion is divided hy sl partition in the manner shown. 
This partition is most simply formed out of a piece of light 
galvanized iron of proper width and hight having the bot- 
tom and the two sides turned at a right angle for the pur- 
pose of nailing it in place. Where the siding of the barn is 
nailed in place vertically intakes may be formed by using 
two strips of galvanized iron formed up as just described, 
nailing them on opposite sides, each with the open end 
down, thus forming two arms, one outside and the other in- 
side extending through the stable ceiling with the two con- 
necting at the top through an opening cut in the siding. 

Where masonry walls are being constructed for stables 
the intakes are readily formed in the building of them by 
placing in the wall a proper form. The forms may be hol- 
low building tile, drain tile or shapes in wood providing the 
desired capacity, simply set in the place desired and the 
wall built about them. 

From the statements made relating to the principles of 
ventilation, in the preceding section, it follows that the area 
of cross-section of both the outtakes and the intakes must de- 
pend in an important degree upon the hight of the out- 
take. If the ventilating shaft is low then it must have a 
sufficiently larger cross-section to compensate for the less 
velocity of air current in the flue which is always associated 
with short shafts. In my earlier writing it was stated that 
a ventilating flue 2x2 feet through which the air moved at 
the rate of 295 feet per minute, or a little more than 3 miles 
per hour, gave sufficient air for 20 dairy cows. This state- 
ment does not mean that any flue 2x2 feet will carry out of 
the stable sufficient air for 20 cows. Such a flue can do so 
only when the velocity of the air current is rather more than 
3 miles per hour. 

Let us refer back to the table on page 56. Take the 
column for the 20 foot outtake. These cubic feet of flow 
per hour for the one-foot flue also mean velocity in feet per- 



120 Ventilation. 

hour, and hence if we divide these numbers by 60 the result 
will be the velocity in feet per* minute. Doing this we get 
the round numbers 97, 307, 434, 532, and 615 feet respect- 
ively for stables which are warm enough so that the air in 
the flue is 1°, 10°, 20°, 30°, and 40° warmer than the air 
outside. But these are theoretical velocities, no allowance 
having been made for friction and other resistance to flow. 
It is quite likely that the actual velocities might not be more 
than one-half those computed. If so then only the last three 
differences in temperature between the air in the outtake 
and that out doors, namely 20°, 30°, and 40° will permit a 
20-foot flue to supply air enough for 20 cows when its size 
is 2x2 feet. As the cows must breathe all of the time and as 
there are times when there is little or no effective wind, dif- 
ference in temperature must chiefly determine the dimen- 
sions of the outtake and intakes and the two should be ap- 
proximately equal in area of cross-section. The difference 
between the stable temperature and that of the outside air 
as given on page 66 ranges from 24° to 61° and averages 
39°. The temperature in the ventilating flue will certainly 
average materially below that in the stable and as it is the 
temperature in the ventilating flue, compared with that out- 
side, which determines the draft, the mean effective differ- 
ence of temperature will be found to average materially less 
than 39° and probably nearer 20° than 30°. With a tem- 
perature difference of 25° a 30-foot shaft will give just 
about the required flow. The conclusion which should gov- 
ern practice, therefore, is : Outtakes and intakes for horses 
and cows should provide not less than 30 square inches per 
head when the outtake has a hight of 30 feet; if the outtake 
is shorter the area should he greater, if higher it may he 
less. A 20-foot outtake would require about 36 square 
inches per head instead of 30. 

Ventilation for Swine and Sheep. 

In the construction of quarters for both swine and sheep 
it has been the practice to build lower ceilings and quite 



Ventilation of Piggery. 121 

generally lower stables for them than for horses and cattle. 
Both kinds of animals being small and given the freedom of 
the stable in common, over-crowding has been more frequent 
and this practice, coupled with the lower ceilings, has re- 
sulted in their suffering from the effects of insufficient ven- 
tilation oftener than horses and than cattle, except in later 
years when the number of individuals in a herd has been 
greatly increased. Sheep are extremely well protected from 
cold by their heavy fleece of wool ; so too, are swine of cold 
climates, when in good condition, by the thick layer of fat 
interposed between the skin and the more vital parts, serv- 
ing the double purpose of nourishment stored against need 
and a weather garment. We doubt very much, however, that 
these protections mean these animals are, necessarily, best 
maintained in severe climates with little or no shelter. In- 
deed, in the admitted absence of exact knowledge to the con- 
trary, there are good reasons for the belief that if both sheep 
and swine could be wintered under temperature conditions 
varying but little from 35° F., except when they are given 
freedom for needed exercise, better results would follow 
than with simple protection from winter storms, provided 
ample ventilation always went with the warmer housing. 
The thorough insulation nature has provided for the bodies 
of these animals makes it necessary that a larger percent of 
the heat produced in the body must be wasted through 
breathing and, for this reason, it may be expected that they 
will thrive better in a somewhat colder air than will cattle, 
but only enough colder to remove the animal heat through 
the relatively smaller surface. 

For the reasons stated, if sheep and swine are housed, 
relatively larger air movement should be continuously 
maintained through the stable, and for the additional one 
that they breathe more air per hour in proportion to their 
weight. Then because the stables are lower, the outtakes 
shorter, and the difference in temperature less and the wind 
velocities as well, it is necessary to provide relatively larger 
outtakes and intakes. If the minimum movement of air 
through a 1-foot outtake 20 feet high is taken at one-half the 



122 



Ventilation. 



value in the table, page 56, where the temperature difference 
between the air in the flue and that outside is 10°, it will 
be 9,204 cubic feet per hour ; with this rate of flow and on 
the basis of 1,392 cu. ft. and 917 cu. ft. of fresh air per hour 
and per head for swine and sheep respectively there should 
be provided an area of 22 sq. in. per head for swine and 15 
sq. in. for sheep for both outtake and intake flues. If the 
outtake flue has a hight of only 15 feet then the number of 
square inches should be not less than 26 for swine and 17 
square inches for sheep per head for outtake and intake flues. 
For 16 swine provided for, as represented in the floor plan, 
htahe i North side t IntaKe 



Feed alley 



Bedroom 



Feed floor 



D 



Bedroom 



\ 



feed floor 



D 



I OuffaKe 

\ 

Feed floor 



Bedroom [ 



Feed floor 



Bedroom 



D 



'' Ir}tahe 



w 



^InlaKe 



w 



■ Intake 



w 



Hntake 



Fig. 61.— Showing floor-plan and ventilation of a piggery. The outtake 
extends to within 12 inches of the floor and admits air on four sides. 



Fig. 61, the outtake would need to be not less than 18x18 
inches inside with a hight of 20 feet ; and 20x20 inches if 
the hight is 15 feet. With the outtake located centrally and 
consisting of a single flue it has the maximum efficiency 
and a minimum cost. 

In the next illustration. Fig. 62, is represented both floor 
plan and elevation of a sheep stable with a ventilation sys- 
tem installed which is both incomplete and inadequate. Ob- 
serve that the outtakes all terminate below the level of the 
ridge of the roof, which both lessens their efficiency and ren- 
ders them liable to reverse draft when the wind is in one 
- direction. In the 80 feet covered by the 10 pens there are 



Ventilation of Sheep Stables. 



123 



provided as many outtakes, each ^x^^ inches and less than 15 
feet high. The space ventilated should accommodate at 
least 50 sheep ; each of the 10 outtakes should then have had 
a cross-section of 85 instead of 36 sq. in. as they do possess. 
A single central outtake 28x28 inches, rising directly 




i_ ~— i 



Fig. 62. — Showing floor-plan and elevation of sheep stable in which the 
outtakes are too short, too small and more numerous than needed; 
and where no intakes have been provided, as should have been. 

through the ridge of the roof 20 feet above the stable floor, 
would give much more efficient ventilation. Two main flues 
18x21 inches placed one-third the distance from either end 
would be rather better than a single central flue. Intakes 
discharging air in at the ceiling and drawing it from near 
the ground level outside should be distributed along each 
side with openings 3x12 inches, 20 of them, 10 on a side. 

Yentilation of Poultry Houses. 

So soon as an attempt is made to house any considerable 
number of hens in warm winter quarters, not made so with 



124 Ventilation. 

the aid of artificial heat, provision for ventilation becomes 
imperative if healthful conditions are desired. It has been 
stated that a hen breathes about 1 . 2 cubic feet of air per 
hour. In one hour 50 hens would respire 60 cubic feet, 
highly charge it with moisture and raise its temperature to 
near 97 ^ This is 2.68 per cent of the volume of air con- 
tained in a room 20x16x7 feet, the space commonly allotted 
to this number of birds. There is heat enough in 60 cubic 
feet of air at 97° to represent 

97X60=5,820 cu. ft. raised 1°. 
The total air in the room in question is 2,240 cu. ft. Sup- 
pose this has a temperature of 20° ; this is heat enough to 
represent, taking out the 60 cu. ft. the hens have breathed, 

2,180X20=43,600 cu. ft. raised 1°. 
If we now add these products we have 

43,600+5,820=49,420 cu. ft. raised 1°. 
Dividing this total by the total amount of air in the room 
we get 

49,420-^^2,240=22°. 
That is to say the 50 hens, by breathing 60 cubic feet of 
air out of the 2,240 and warming it to 97°, letting it again 
mix with the balance in the room, have raised the general 
temperature from 20° to 22°. It is clear, from these fig- 
ures that 50 hens are unable to warm through many degrees 
any large volume of air. 

Prof. Gowell, of the Maine Agricultural Experiment Sta- 
tion, recognizing this fact in a practical way, has designed 
for poultry houses a sleeping chamber, by enclosing the 
roosts in a floored space just under the ceiling and provid- 
ing the entire front side of this chamber with doors of 
rather light canvass, hinged at the ceiling so that on cold 
nights these may be closed down for warmth. The size of 
the sleeping chamber recommended by Gowell is less than 
4x4x20 feet and the only ventilation provided is through the 
■canvass doors. It is clear that the smaller volume of air 
enclosed in the sleeping chamber would be maintained at a 
higher temperature unless the air was changed in it at a 



Ventilation of Poultry Houses. 



125 



more rapid rate. Taking the capacity of the chamber at 320 
cubic feet and supposing that its air is changed once per 
hour and replaced with that at 20°, breathing alone, not al- 
lowing for loss, should maintain a temperature 14° higher 
or 34°, the air of the chamber having one-seventh the vol- 
ume of the room considered above. But if the air in 
the chamber is changed but once per hour it would contain 
18.75 per cent of air once breathed, instead' of 3.3 per cent, 
the standard we have assumed as possibly permissible for 




Cellar to warm 
Poultry house 



Fig. 63. — Showing method of ventilating a poultry house. A is sleeping 
chamber without floor; B is flue to admit warmed air to sleeping 
chamber from cellar if one is provided; C is duct to admit air from 
floor of house to cellar to be warmed. If no warming cellar is pro- 
vided the floor should be cemented. 



COWS. We doubt if under the conditions recommended by 
Gowell the air Avill be changed oftener than once or twice 
per hour and such a rate does not appear to be sufficient. 
In view of the considerations here presented we have de- 
signed the poultry house represented in Fig. 63. As shown, 
it is 16x20x7 feet and intended for 50 hens. To guard 
against low temperature a cellar is suggested under the 
whole floor with provision for air to circulate as shown in 
the drawing, thus utilizing the ground heat for warming. 
If a location can be chosen which permits all but the south 



126 Ventilation. 

front to be largely in the bank and a cement floor is pro- 
vided to conduct the heat of the subsoil into the house 
through the general floor, this will do much for warmth. 
Indeed, with four long windows on the south, we do not 
hesitate to recommend, for severe climates, placing the 
chicken house in a bank with the floor cemented and 18 to 
24 inches below the ground level in front. Such a house, 
because it can be more thoroughly ventilated, will be less 
damp and more wholesome. 

For houses wholly above ground, the walls must be 
closely and warmly constructed. A very warm wall may 
be made with 2x8 's set 3 feet apart, covered with drop sid- 
ing outside and matched fencing inside or, what would be 
best, a light weight of galvanized iron nailed closely and 
vertically to the studding, filling the spaces between the 
studding compactly with dry fibrous peat. The ceiling 
likewise should be similarly built so that no air may escape 
through it. A very warm ceiling could be made by tightly 
packing the space above very closely with marsh hay, rep- 
resented in Fig. 63. A very warm poultry house can 
be made by using 2x8 studding, covered with drop sid- 
ing outside and only with a light weight of galvanized 
iron inside, with the space between the studding closely 
packed with fine marsh hay and treating the ceiling as 
already described. The closely packed hay makes one of 
the best of nonconductors, while the metal makes the walls 
and ceiling both air-tight and sanitary in every way. 

It will be clear from statements made on page 63 that 
where the ventilating flue for poultry houses may rise 16 
feet above the floor the cross-section of both outtakes and 
intakes should provide some 4 square inches per bird, or 
at the rate of 200 square inches for each 50 hens or their 
equivalent. 



INDEX. 



Abbot, Dr. C. G., letter, 84: relative 
intensity of sky lig-ht, 84; best window 
exposure, 85: form of window for max- 
imum liffhting-, 85: comparative 
amount of lig-ht from sky and sun. 85. 

Air. amount breathed b.v different an- 
imals. 9: amount inadeauate without 
definite provision, 19: amount used in 
combustion. 8: composition, of pure, 
13, — of once breathed. 14. 68.— of stable, 
70: continuous flow necessar.v. 17: cost 
of warming, 66: density, of pure at dif- 
ferent temperatures,68, — of respired at 
different temperatures. 68, — difference 
of, demonstrated. 69: experimental de- 
monstration of chang-es in respired, 
13, 15, 16. 69: formulas for computing- 
flow of, 47, 48, 55: graphic representa- 
tion of amount breathed, 10; once 
breathed loses in food value. 11: rate 
of flow in outtakes, 56, 57, 59, 60, 66,— 
due to wind pressure. 47, 57.— due to 
wind suction. 48, 57,— due to difference 
in temperature. 53. 55, 56, — due to hu- 
midity, 61; specific heat of, 66: volume 
of. required for dwelling-s, 36, 41, 90,— 
for stables, 41,42.43. 62,— for cows and 
horses, 42, 43, 120,— for sheep and 
swine. 43, 121,— for poultry, 41, 42, 63, 
126,— breathed per hour, 10. 

Armsby, Dr. H. P.. amount of moisture 
transpired by steer, 34. 

Blood, aeration of, 6: corpuscles, 6.— ex- 
tent of surface, 7,— function of, 6: 
movement of, 7, 

■Carbon dioxide, amount in air, 13. 14, — 
in stable air. 37, 40, 70: as index of air 
purity, 36: how removed from system, 
6. 

Carnelly, standard of air purity, 36. 

Clarke, composition of air, 13. 

Cow. air breathed per hour, 9. 10: cross- 
section of ventilating- flue for, 42, 120: 
heat produced by, 64: moisture trans- 
pired by, 34: ventilation experiment 
with. 28, 37, 38, 70: ventilation of 
stables for, 109-120. 

Colin, amount of air respired b.v differ- 
ent animals, 9. 

De Chaumont. standard of air purity 
for man, 36: volume of air movement 
for man, 36. 

Diseases, susceptibility to contagious, 

24, 89. I 



Dwelling-s, ventilation of, 88, — by fire- 
places. 88, 95— by stoves, 91, — when 
warmed with hot air, 93,— when warm- 
ed witli steam or hot water. 73. 100. 

Fireplace, ventilation by. 88. 95. 

Florham Park stables, 53, 59. 60. 

Flues, flow of air in, theoretical, 56, 57. — 
methods of computmg-. 52. 55.— ob- 
served. .59. 60. 66: for houses. 92. 97. 98. 
101: for school-houses. 103. 106; for 
stables. 107. 109. 111-118. 123. 126: hig-ht, 
60: size, 60, 63. 120, 121, 126; capacity 
of. 56. 57, 63, 122. 

Gowell, G. M., ventilation of poultry 
houses. 124. 

Haldane, standard of air purity, 36. 

Heat, amount g-iven off by cow. 64: mo- 
tive power in ventilation. 52. 56. 67: 
utilized in ventilation. 71: specific. 66. 

Heating-, poultry houses with sub-cel- 
lar. 125: rural school-houses. 103, 106; 
with fireplaces, 88. 95: witli hot-air 
furnaces, 96: with steam and hot 
water, 100; with stoves. 91, 106. 

Hen, air breathed per hour. 9. — required 
in ventilation. 41. 42.— warmed by 
breathing-. 124: moisture thrown off 
by, 28; outtakes and intakes for, 126. 

Horse, air breathed per hour. 9, 10.— vol- 
ume of, for g-ood ventilation, 41, 42; 
area of outtakes and intalces for. 120, 

House, warming- and ventilation, 88-102; 
type of, readily warmed and ven- 
tilated, 102: ventilated, with fire- 
place. 88-95,— with hot-air furnaces, 
96.— when heated with steam or hot 
water, 100.— witli stoves. 91. 

Humidity, as motive power in ventila- 
tion. 60-63: of air in U. S., 34; of re- 
spired air, 14, 32. 

Intakes, 49, 72. 74. 75: for dairy stables, 
59. 72. 75. 111-114. 117. 118: for base- 
ment stables. 118: for dwelling-s, 
92,101: for pig-g-eries. 122: for poultry 
houses, 125; for schoolhouses. 103, 105, 
106: size, 120. 122. 123. 126: types of, 109; 
velocity of flow throug-h, 59. 

Jordan, Dr, W. H., composition of stable 
air. 37, 73; heat g-iven off by cow, 64. 

Jordan. E. L., air movement throug-h 
stable. 65; temperature of stable, 65. 

Lamp, oil burned by, 20. 90; ventilation 
experiments with, 20-23, 27. 



128 



Index. 



Light. Abbot, views and observations 
on, 84; amount admitted by windows, 
85, 86. 87; cannot be depended upon 
for complete destruction of germs, 
83; destroyer of disease germs, 81; for 
dwellings and stables, 78; from whole 
sky compared with sun. 85; most in- 
tense from south sky, 85; Weinzirl. on 
destruction of disease germs by, 82. 

Magnesium ribbon, combustion in pure 
and breathed air, 12. 13. 

Man, air breathed per hour, 9. 10,— re- 
■ Quired in ventilation, 41, 42,— standard 
of purity for, 36; amount of moisture 
transpired by. 33. 

Moisture, amount transpired by man, 
32,— by cow, 33,— amount of air re- 
quired to remove, 33. 34: as motive 
power in ventilation, 60; effect on air 
density, 68; in respired air, 14. 

Nitrogen, amount in air, 13, 14. 

Offices, ventilating. 73, 75. 

Outtake, cross-section for. 120. 121, 126; 
defective shelter for. 50. 51. 52: dimen- 
sions, for cows and horses, 62. 120, — for 
swine and sheep. 63, 121. — for poultry, 
63, 126; for horses, 92, 97. 100; for 
school-houses. 102. 106: for stables. 74, 
107, 109. 111-117.122. 123. 125; hight of , 
53, 56, 63, 126; location of, 74; essential 
characteristics of. 107: proper termi- 
nation for. 53; table of rate of flow 
through, 56. 57. 59, 60. 'o^. 

Oxygen, amount consumed by man. at 
different temperatures. 77 : amount in 
air. 13. 14; effects of deficiency of , 24: 
required in combustion, 1, 8. 

Pigs, airbreathedperhour, 9, 10, — move- 
ment for ventilation, 41, 43; venti- 
lation for. 63. 121, 123. 

Poultry, ventilation for, 63. 125. 

Pressure, due to difference in temper- 
ature. 52. 55: due to humidity. 60: due 
to wind impact. 47; due to wind suc- 
tion, 48. 

School-house, warming and ventilation 
of, 73. 103, 106. 

Seguin. moisture transpired by man. 33. 

Shaw, W. N., velocity of air in flues due 
to different wind velocities, measured 
by, 58. 

Sheep, air breathed per hour. 9, 10.— re- 
quired for ventilation, 41, 43: ventila- 
tion for. 121, 124. 

Shelters for outtakes, 50 — 53. 



Stables, air movement to prevent mois- 
ture condensation, 33, 34; composition, 
of air in. 37. 39. 70; lighting for. 79: 

■ maximum lighting effect for. 86; per- 
meability of walls to ail". 37. 38: ven- 
tilation of, 107; windows for, 80, 81,. 
86, 87. 

Stoves, as ventilators, 91, 106. 

Temperature, best for room and stable-- 
76; computed maintenance for sta- 
bles. 65: observed in stables. 66, 70;: 
difference of, in ventilation, 56. 58. 

Tobin tubes, 75. 

Twombly, H. McK., stables of, 53, 59. 

Ventilation, and maintenance of tem- 
perature 64: demonstration chamber 
for, 20: experiments, with cows. 28. 38, 
66, 70,— with hens, 22, 23.— with lamp, 
20, 23: extra heat needed for not great, 
67; flues, improper installation of,. 
50.— shelter for, 51-53; for sheep and 
swine, 120: for poultry. 123: full utili- 
zation of waste heat in .securing. 67; 
maintenance of temperature to in- 
crease, 71 ; mean effective difference in 
temperature for. in houses. 58, — in 
stables. 58; motive power in, wind im- 
pact. 47. — wind suction. 48.— differ- 
ence in temperature, 52, 55. — humidity 
of air, 60; mean effective wind veloc- 
ity for, 58; mean effective difference 
in temperature for, in houses. 58. — 
in stables, 58: need of increasing, 
18. 88: of body tissues. 3: of dairy 
stables, 109: of houses already 
built, 90; of new and remodeled 
houses, 94; of school-houses, 102; of 
stables. 107: power required in, 46; 
practice of, 76: principles of. 45; 
principles of construction for. 73; 
problem of. stated, 41: serious effect* 
follow insufficient, 24; through flre- 
place. 88: through stoves, 91, 106. 

Weinzirl. Dr. John, efficiency of light 
as a germicide. 82. 

Wind, action in producing ventilation, 
49: flow, due to impact of, 47. 57. — due 
to suctional effect of. 48, 57: mean ef- 
fective velocity of. 58.— may be very 
small or nil. 62; pi'essure of, 47; suc- 
tional effect of. 48. 

Windows, efficiency of. 86-88: faulty 
arrangement of . 80: forni and expos- 
ure of for maximm lighting. 81; num- 
ber, size and exposure, 79: south ex- 
posure best. 



THE SOIL 

By F. H. KING 

Professor of Agricultural Physics in the University of Wisconsin. 1888-1901 ; 
Chief of the Division of Soil Management, U. S. Department of Agricul- 
ture, 1901-1904. 

Author of "Irrigation and Drainage," 1899; "Physics of Agricultiire," 1901 ; 
"Tillage, Its Philosophy and Practice," "The Necessity and Practice of 
Drainage", in Cyclopedia of American Agriculture, 1907 ; "Drainage ^ and 
"Irrigation," in The Standard Cyclopedia of Modem Agriculture, (British) 
1908. 

303 pages, 7x5 inches, 45 illustrations.— $1.68 prepaid. 



CONTENTS 

Introduction ^~ 2" 

The Nature, Functions, Origin and Wasting of Soils 27-69 

Texture, Composition and Kinds of Soils 70-106 

Nitrogen of the Soil 107-134 

Capillarity, Solution, Diffusion and Osmosis 135-153 

Soil Water 154-183 

Conservation of Soil Moisture 184-206 

The Distribution of Roots in the Soil 207-217 

Soil Temperature 218-238 

The Relation of Air to Soil 239-252 

Farm Drainage 253-267 

Irrigation 268-275 

Physical Effects of Tillage and Fertilizers 276-294 



"I consider it a most desirable addition to our agricultural literature, and a 
distinct advance over previous treatises on the same subject, not only for 
popular use, but also for students and specialists." * * * ' 

Dr. E. W. Hilgard, Director Calif. State Agr. Exp. Station. 

"For practicability and entertaining power combined this work is at the head 
of its class." — The Boston Traveller. 

"The manual is brief, accurate, comprehensive and hits the practical point 
every time." — Independent. 

"It is a book which progressive farmers will come to' regard as one of the 
essential implements of farm life." — Boston Daily Advertiser. 

"The great point about the book, in our opinion, is its thorough practical 
nature. Personally the writer is acquainted with probably all modem works 
on this vitally important question * * * ; but we certainly never derived 
so real benefit from the perusal of any two, nay, even three or four works of 
this character, as from the one now under consideration." — E. Kemp Toogood, 
F. R. H. S. in Royal Cornwall Gazette. 



IRRIGATION AND DRAINAGE 

By F. H. KING 

Professor of Agricultural Physics in the University of Wisconsin, 1888-1901 : 
Chief of the Division of Soil Management, U. S. Department of Agriculture 
1901-1904. ' 

Author of "The Soil," 1895 ; "Physics of Agriculture," 1901 ; "Tillage, Its 
Philosophy and Practice", "The Necessity, and Practice of Drainage", in 
Cyclopedia of American Agriculture, 1907 ; "Drainage" and "Irrigation In 
The Standard Cyclopedia of Modern Agriculture, (British), 1908. 
502 pages, 7x5 inches, 163 illustrations. — $1.66 prepaid. 



CONTENTS 

Introduction 1_ qq 

PART I. IRRIGATION CULTURE 

The Extent and Geographic Range of Irrigation 66- 90 

The Conditions which make Irrigation Imperative, Desirable, or Neces- 
sary 91-116 

The Extent to which Tillage may take the Place of Irrigation 117-170 

The Increase of Yield Due to Irrigation in Humid Climates 171-195 

Amount and Measurement of Water for Irrigation 196-221 

Frequency, Amount and Measurement of Water for Single Irrigations.. 222-247 

Characier of Water for Irrigation 248-268 

Alkali Lands 269-289 

Supplying Water for Irrigation '. . 290-328 

Methods of Applying Water in Irrigation 329-402 

Sewage Irrigation 403-414 

PART II. FARM DRAINAGE 

Principles of Drainage .' 415-466 

Practical Details of Underdrainage 467-492 

"To the ordinary farmer the title of this book is somewhat misleading. If 
he is not In an irrigating district, and has no wet lands, he will at once con- 
clude, on seeing the title, that the subjects treated in the book do not concern 
him to the extent of $1.50. If, however, by chance he has the opportunity of 
reading the book he will change his opinion. The proper amount of water 
available at the right time is essential to successful or profitable farming In any 
country, and, therefore, Professor King opens his books with some general re- 
marks on the importance of water ; on the texture of the soil necessary to con- 
serve the moisture ; and follows it up with the report of some experiments show- 
big the amount of water used by plants, which will be a surprise to the farmers 
who have not investigated the subject. The method by which the water is ob- 
tained by plants and exhaled ; the remarkable way in which the plants them- 
selves control the demand, economize water, so to speak ; the mechanism by 
which the roots get hold of the moisture ; the extent of the root surface ; all 
these are treated in a wonderfully interesting way in this book, and are of all- 
absorbing interest to the man who is farming for dear life, and, if he Is properly 
awake to the Importance of the subject, will prove as interesting as a novel 
We regard it as one of the most valuable contributions made to the 
science of agriculture in recent years." — Wallaces' Farmer. 

"But althouffh the author travels far and wide in search of examples and re- 
sults in Illustration of the principles which he advances, and so far Introduces 
matter which Is of great importance in the discussion of, irrigation proper, yet 
the bulk of what he has written is full of instruction of the most practical 
character for the rent-paying farmer." — Manchester (England) Guardian. 



orr> 1 



